feat: persist last active tab and preserve per-tab navigation state

lib/features/artists/presentation/artist_posts_screen.dart

@@ -3,10 +3,10 @@ import 'dart:convert';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:go_router/go_router.dart';
 import 'package:url_launcher/url_launcher.dart';
 
 import '../../../app/app.dart';
+import '../../../app/app_navigator.dart';
 import '../../../app/responsive.dart';
 import '../../../backend/backend.dart';
 import '../../../core/utils/result.dart';
@@ -791,12 +791,10 @@ class _ArtistPostsScreenState extends ConsumerState<ArtistPostsScreen> {
                                       settings.mediaQualityMode),
                                   favoriteKeys: favoriteKeys,
                                   viewedKeys: viewedKeys,
-                                  onOpen: (post) => context.push(
-                                    '/post/${post.providerId}/${post.id}',
-                                    extra: PostNavigationContext(
-                                      currentPost: post,
-                                      posts: displayedPosts,
-                                    ),
+                                  onOpen: (post) => AppNavigator.openPost(
+                                    context,
+                                    post: post,
+                                    postsList: displayedPosts,
                                   ),
                                   onFavorite: (post) async {
                                     if (favoriteKeys.contains(post.cacheKey)) {

lib/features/artists/presentation/artists_screen.dart

@@ -7,6 +7,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
 import '../../../app/app.dart';
+import '../../../app/app_navigator.dart';
 import '../../../app/responsive.dart';
 import '../../../backend/backend.dart';
 import '../../../core/utils/result.dart';
@@ -1574,12 +1575,10 @@ class _FavoriteArtistMediaStrip extends ConsumerWidget {
                 final isVideo = MediaUrlSelector.isVideo(post);
                 return InkWell(
                   borderRadius: BorderRadius.circular(14),
-                  onTap: () => context.push(
-                    '/post/${post.providerId}/${post.id}',
-                    extra: PostNavigationContext(
-                      currentPost: post,
-                      posts: posts,
-                    ),
+                  onTap: () => AppNavigator.openPost(
+                    context,
+                    post: post,
+                    postsList: posts,
                   ),
                   child: Container(
                     decoration: BoxDecoration(

lib/features/collections/presentation/collection_details_screen.dart

@@ -3,6 +3,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
 import '../../../app/app.dart';
+import '../../../app/app_navigator.dart';
 import '../../../app/responsive.dart';
 import '../../../backend/backend.dart';
 import '../../../shared/widgets/adaptive_scaffold.dart';
@@ -167,12 +168,10 @@ class CollectionDetailsScreen extends ConsumerWidget {
                   mediaQualityMode:
                       MediaQualityMode.fromName(settings.mediaQualityMode),
                   favoriteKeys: favoriteKeys,
-                  onOpen: (post) => context.push(
-                    '/post/${post.providerId}/${post.id}',
-                    extra: PostNavigationContext(
-                      currentPost: post,
-                      posts: items,
-                    ),
+                  onOpen: (post) => AppNavigator.openPost(
+                    context,
+                    post: post,
+                    postsList: items,
                   ),
                   onFavorite: (post) async {
                     if (favoriteKeys.contains(post.cacheKey)) {

lib/features/favorites/presentation/favorites_screen.dart

@@ -7,6 +7,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
 import '../../../app/app.dart';
+import '../../../app/app_navigator.dart';
 import '../../../app/responsive.dart';
 import '../../../backend/backend.dart';
 import '../../../shared/widgets/adaptive_scaffold.dart';
@@ -970,12 +971,10 @@ class _FavoritesScreenState extends ConsumerState<FavoritesScreen> {
       mediaQualityMode: MediaQualityMode.fromName(settings.mediaQualityMode),
       favoriteKeys: posts.map((post) => post.cacheKey).toSet(),
       downloadedKeys: downloadedKeys,
-      onOpen: (post) => context.push(
-        '/post/${post.providerId}/${post.id}',
-        extra: PostNavigationContext(
-          currentPost: post,
-          posts: posts,
-        ),
+      onOpen: (post) => AppNavigator.openPost(
+        context,
+        post: post,
+        postsList: posts,
       ),
       onFavorite: (post) =>
           ref.read(favoritesControllerProvider.notifier).remove(post),

lib/features/feed/presentation/feed_screen.dart

@@ -8,6 +8,7 @@ import 'dart:async';
 import 'package:cached_network_image/cached_network_image.dart';
 
 import '../../../app/app.dart';
+import '../../../app/app_navigator.dart';
 import '../../../app/responsive.dart';
 import '../../../backend/backend.dart';
 import '../../../core/utils/result.dart';
@@ -331,12 +332,10 @@ class _FeedScreenState extends ConsumerState<FeedScreen>
                             selectionMode: _selectionMode,
                             selectedKeys: _selectedKeys,
                             gridMode: settings.gridMode,
-                            onOpen: (post) => context.push(
-                              '/post/${post.providerId}/${post.id}',
-                              extra: PostNavigationContext(
-                                currentPost: post,
-                                posts: state.posts,
-                              ),
+                            onOpen: (post) => AppNavigator.openPost(
+                              context,
+                              post: post,
+                              postsList: state.posts,
                             ),
                             onPreview: (post) => _showPreview(context, post),
                             onToggleSelected: (post) => _toggleSelected(post),
@@ -392,7 +391,7 @@ class _FeedScreenState extends ConsumerState<FeedScreen>
   void _openRandom(List<Post> posts) {
     if (posts.isEmpty) return;
     final post = posts[Random().nextInt(posts.length)];
-    context.push('/post/${post.providerId}/${post.id}', extra: post);
+    AppNavigator.openPost(context, post: post, postsList: posts);
   }
 
   Future<void> _applySearchQuery(String query) async {

lib/features/post/presentation/post_details_screen.dart

@@ -8,6 +8,7 @@ import 'package:share_plus/share_plus.dart';
 import 'package:url_launcher/url_launcher.dart';
 
 import '../../../app/app.dart';
+import '../../../app/app_navigator.dart';
 import '../../../app/app_strings.dart';
 import '../../../app/motion.dart';
 import '../../../app/responsive.dart';
@@ -872,7 +873,7 @@ class PostDetailsScreen extends ConsumerWidget {
   }
 
   void _openSimilar(BuildContext context, WidgetRef ref, Post post) {
-    context.push('/post/${post.providerId}/${post.id}/similar', extra: post);
+    AppNavigator.openSimilarPosts(context, post: post);
   }
 
   Future<void> _openSourcePage(WidgetRef ref, Post post) async {
@@ -888,7 +889,16 @@ class PostDetailsScreen extends ConsumerWidget {
   }
 
   void _replacePost(BuildContext context, Post post) {
-    context.replace('/post/${post.providerId}/${post.id}', extra: post);
+    Navigator.of(context).pushReplacement(
+      MaterialPageRoute<void>(
+        builder: (ctx) => PostDetailsScreen(
+          providerId: post.providerId,
+          postId: post.id,
+          initialPost: post,
+          postsList: postsList,
+        ),
+      ),
+    );
   }
 
   void _close(BuildContext context) {

lib/features/post/presentation/similar_posts_screen.dart

@@ -1,8 +1,8 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:go_router/go_router.dart';
 
 import '../../../app/app.dart';
+import '../../../app/app_navigator.dart';
 import '../../../app/responsive.dart';
 import '../../../backend/backend.dart';
 import '../../../core/utils/result.dart';
@@ -98,9 +98,9 @@ class SimilarPostsScreen extends ConsumerWidget {
                           MediaQualityMode.fromName(settings.mediaQualityMode),
                       favoriteKeys: favorites,
                       viewedKeys: viewed,
-                      onOpen: (post) => context.push(
-                        '/post/${post.providerId}/${post.id}',
-                        extra: post,
+                      onOpen: (post) => AppNavigator.openPost(
+                        context,
+                        post: post,
                       ),
                       onFavorite: (post) =>
                           _toggleFavorite(ref, post, favorites),

lib/features/settings/presentation/hidden_posts_screen.dart

@@ -1,9 +1,9 @@
 import 'package:cached_network_image/cached_network_image.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:go_router/go_router.dart';
 
 import '../../../app/app.dart';
+import '../../../app/app_navigator.dart';
 import '../../../backend/backend.dart';
 import '../../../core/utils/result.dart';
 import '../../../shared/widgets/adaptive_scaffold.dart';
@@ -62,9 +62,9 @@ class HiddenPostsScreen extends ConsumerWidget {
                     item: item,
                     onOpen: item.post == null
                         ? null
-                        : () => context.push(
-                              '/post/${item.post!.providerId}/${item.post!.id}',
-                              extra: item.post,
+                        : () => AppNavigator.openPost(
+                              context,
+                              post: item.post!,
                             ),
                     onRestore: () async {
                       await ref

lib/features/viewed/presentation/viewed_screen.dart

@@ -7,6 +7,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
 import '../../../app/app.dart';
+import '../../../app/app_navigator.dart';
 import '../../../app/responsive.dart';
 import '../../../backend/backend.dart';
 import '../../../shared/widgets/adaptive_scaffold.dart';
@@ -142,12 +143,10 @@ class _ViewedScreenState extends ConsumerState<ViewedScreen> {
                 mediaQualityMode:
                     MediaQualityMode.fromName(settings.mediaQualityMode),
                 favoriteKeys: favoriteKeys,
-                onOpen: (post) => context.push(
-                  '/post/${post.providerId}/${post.id}',
-                  extra: PostNavigationContext(
-                    currentPost: post,
-                    posts: allPosts,
-                  ),
+                onOpen: (post) => AppNavigator.openPost(
+                  context,
+                  post: post,
+                  postsList: allPosts,
                 ),
                 onFavorite: (post) => _toggleFavorite(
                   ref,
@@ -260,12 +259,10 @@ class _ViewedScreenState extends ConsumerState<ViewedScreen> {
                       isFavorite: favoriteKeys.contains(item.post.cacheKey),
                       isRu: isRu,
                       onOpen: () {
-                        context.push(
-                          '/post/${item.post.providerId}/${item.post.id}',
-                          extra: PostNavigationContext(
-                            currentPost: item.post,
-                            posts: allPosts,
-                          ),
+                        AppNavigator.openPost(
+                          context,
+                          post: item.post,
+                          postsList: allPosts,
                         );
                       },
                       onFavorite: () => _toggleFavorite(