Add provider tag suggestions and tag categories

lib/backend/services/search_service.dart

@@ -1,11 +1,14 @@
 import '../../core/utils/result.dart';
 import '../models/search_history.dart';
+import '../models/tag_suggestion.dart';
+import '../providers/provider_manager.dart';
 import '../repositories/search_repository.dart';
 
 class SearchService {
-  SearchService(this._repository);
+  SearchService(this._repository, [this._providerManager]);
 
   final SearchRepository _repository;
+  final ProviderManager? _providerManager;
 
   List<String> parseTags(String query) {
     return query
@@ -35,21 +38,21 @@ class SearchService {
 
   Future<Result<List<String>>> autocomplete(String prefix,
       {int limit = 10}) async {
-    final recent = await _repository.recent(limit: 100);
-    return recent.fold(
-      onSuccess: (items) {
-        final needle = prefix.toLowerCase();
-        final values = <String>{};
-        for (final item in items) {
-          for (final tag in item.tags) {
-            if (tag.toLowerCase().startsWith(needle)) values.add(tag);
-          }
-        }
-        return Success(values.take(limit).toList());
-      },
+    final result = await autocompleteDetailed(prefix, limit: limit);
+    return result.fold(
+      onSuccess: (items) => Success(items.map((item) => item.name).toList()),
       onError: Error<List<String>>.new,
     );
   }
 
+  Future<Result<List<TagSuggestion>>> autocompleteDetailed(
+    String prefix, {
+    int limit = 10,
+  }) async {
+    final manager = _providerManager;
+    if (manager == null || prefix.trim().isEmpty) return const Success([]);
+    return manager.suggestTags(prefix.trim(), limit: limit);
+  }
+
   Future<Result<void>> clearHistory() => _repository.clear();
 }