Add Windows installer script

.gitignore

@@ -1,6 +1,7 @@
 .dart_tool/
 .packages
 build/
+dist/
 /isar.dll
 .idea/
 *.iml

installer/RuleGel.iss

@@ -0,0 +1,40 @@
+#define MyAppName "RuleGel"
+#define MyAppVersion "0.2.0"
+#define MyAppPublisher "RarDog"
+#define MyAppExeName "gel_rule_app.exe"
+
+[Setup]
+AppId={{8B7B8F47-3F16-4E63-8D41-6F2F94938F0E}
+AppName={#MyAppName}
+AppVersion={#MyAppVersion}
+AppPublisher={#MyAppPublisher}
+DefaultDirName={localappdata}\Programs\{#MyAppName}
+DefaultGroupName={#MyAppName}
+DisableProgramGroupPage=yes
+PrivilegesRequired=lowest
+OutputDir=..\dist
+OutputBaseFilename=RuleGelSetup
+SetupIconFile=..\windows\runner\resources\app_icon.ico
+Compression=lzma2
+SolidCompression=yes
+WizardStyle=modern
+ArchitecturesAllowed=x64compatible
+ArchitecturesInstallIn64BitMode=x64compatible
+UninstallDisplayIcon={app}\{#MyAppExeName}
+CloseApplications=yes
+
+[Languages]
+Name: "english"; MessagesFile: "compiler:Default.isl"
+
+[Tasks]
+Name: "desktopicon"; Description: "Create a desktop shortcut"; GroupDescription: "Additional shortcuts:"; Flags: unchecked
+
+[Files]
+Source: "..\build\windows\x64\runner\Release\*"; DestDir: "{app}"; Flags: ignoreversion recursesubdirs createallsubdirs; Excludes: "*.lnk"
+
+[Icons]
+Name: "{group}\{#MyAppName}"; Filename: "{app}\{#MyAppExeName}"
+Name: "{autodesktop}\{#MyAppName}"; Filename: "{app}\{#MyAppExeName}"; Tasks: desktopicon
+
+[Run]
+Filename: "{app}\{#MyAppExeName}"; Description: "Launch {#MyAppName}"; Flags: nowait postinstall skipifsilent