feat(gui): implement Plugins dashboard and Store UI in Flutter

gui/lib/app.dart

@@ -11,6 +11,7 @@ import 'screens/about_screen.dart';
 import 'screens/dreamcast_screen.dart';
 import 'screens/home_screen.dart';
 import 'screens/patcher_screen.dart';
+import 'screens/plugins_screen.dart';
 import 'screens/settings_screen.dart';
 import 'screens/theme_editor_screen.dart';
 import 'screens/tools_screen.dart';
@@ -44,7 +45,7 @@ class _OpenROMAppState extends State<OpenROMApp> {
   String _outputDir = '';
   String _audioCodec = 'flac';
 
-  static const List<int> _mobileScreenIndices = [0, 1, 2, 4];
+  static const List<int> _mobileScreenIndices = [0, 1, 2, 4, 5];
 
   @override
   void initState() {
@@ -143,6 +144,7 @@ class _OpenROMAppState extends State<OpenROMApp> {
       PatcherScreen(theme: theme),
       ToolsScreen(theme: theme),
       DreamcastScreen(theme: theme),
+      PluginsScreen(theme: theme),
       settingsWidget,
       AboutScreen(theme: theme),
       ThemeEditorScreen(
@@ -221,6 +223,11 @@ class _OpenROMAppState extends State<OpenROMApp> {
                     activeIcon: Icon(Icons.construction),
                     label: 'Tools',
                   ),
+                  BottomNavigationBarItem(
+                    icon: Icon(Icons.extension_outlined),
+                    activeIcon: Icon(Icons.extension),
+                    label: 'Plugins',
+                  ),
                   BottomNavigationBarItem(
                     icon: Icon(Icons.settings_outlined),
                     activeIcon: Icon(Icons.settings),

gui/lib/controllers/plugin_controller.dart

@@ -0,0 +1,146 @@
+// OpenROM — Universal ROM Compression Suite
+// M5 Dev | GPL v3
+
+import 'package:file_picker/file_picker.dart';
+import 'package:flutter/foundation.dart';
+import 'package:openrom_core/openrom_core.dart';
+
+import '../models/store_plugin.dart';
+import '../services/plugin_service.dart';
+
+class PluginController extends ChangeNotifier {
+  final PluginService _service;
+
+  List<PluginManifest> _installedPlugins = [];
+  List<StorePlugin> _storeCatalog = [];
+  bool _isLoading = false;
+  String? _errorMessage;
+  String? _statusMessage;
+
+  PluginController({PluginService? service})
+      : _service = service ?? PluginService();
+
+  List<PluginManifest> get installedPlugins =>
+      List.unmodifiable(_installedPlugins);
+  List<StorePlugin> get storeCatalog => List.unmodifiable(_storeCatalog);
+  bool get isLoading => _isLoading;
+  String? get errorMessage => _errorMessage;
+  String? get statusMessage => _statusMessage;
+
+  void clearError() {
+    _errorMessage = null;
+    notifyListeners();
+  }
+
+  /// Refreshes the list of locally installed plugins.
+  Future<void> loadInstalledPlugins() async {
+    _isLoading = true;
+    _errorMessage = null;
+    notifyListeners();
+
+    try {
+      _installedPlugins = await _service.loadInstalledPlugins();
+    } catch (e) {
+      _errorMessage = 'Failed to load installed plugins: $e';
+    } finally {
+      _isLoading = false;
+      notifyListeners();
+    }
+  }
+
+  /// Fetches available store catalog items.
+  Future<void> fetchStoreCatalog({String? endpointUrl}) async {
+    _isLoading = true;
+    _errorMessage = null;
+    notifyListeners();
+
+    try {
+      _storeCatalog = await _service.fetchStoreCatalog(
+        endpointUrl: endpointUrl,
+      );
+    } catch (e) {
+      _errorMessage = 'Failed to fetch plugin store catalog: $e';
+    } finally {
+      _isLoading = false;
+      notifyListeners();
+    }
+  }
+
+  /// Installs a `.orplug` package from a file path.
+  Future<bool> installPluginFromPath(String orplugPath) async {
+    _isLoading = true;
+    _statusMessage = 'Installing plugin...';
+    _errorMessage = null;
+    notifyListeners();
+
+    try {
+      final success = await _service.installPlugin(orplugPath);
+      if (success) {
+        _statusMessage = 'Plugin installed successfully!';
+        await loadInstalledPlugins();
+        return true;
+      } else {
+        _errorMessage =
+            'Failed to install plugin. Check manifest and SHA256 integrity.';
+        return false;
+      }
+    } catch (e) {
+      _errorMessage = 'Error during plugin installation: $e';
+      return false;
+    } finally {
+      _isLoading = false;
+      _statusMessage = null;
+      notifyListeners();
+    }
+  }
+
+  /// Opens file picker for `.orplug` files and installs the selected file.
+  Future<bool> pickAndInstallPlugin() async {
+    try {
+      final result = await FilePicker.platform.pickFiles(
+        type: FileType.custom,
+        allowedExtensions: ['orplug', 'zip'],
+      );
+
+      if (result != null && result.files.single.path != null) {
+        return await installPluginFromPath(result.files.single.path!);
+      }
+    } catch (e) {
+      _errorMessage = 'Failed to pick plugin file: $e';
+      notifyListeners();
+    }
+    return false;
+  }
+
+  /// Uninstalls an installed plugin by ID.
+  Future<bool> uninstallPlugin(String pluginId) async {
+    _isLoading = true;
+    _statusMessage = 'Uninstalling plugin...';
+    _errorMessage = null;
+    notifyListeners();
+
+    try {
+      final success = await _service.uninstallPlugin(pluginId);
+      if (success) {
+        _statusMessage = 'Plugin uninstalled successfully.';
+        await loadInstalledPlugins();
+        return true;
+      } else {
+        _errorMessage = 'Failed to uninstall plugin "$pluginId".';
+        return false;
+      }
+    } catch (e) {
+      _errorMessage = 'Error during plugin uninstallation: $e';
+      return false;
+    } finally {
+      _isLoading = false;
+      _statusMessage = null;
+      notifyListeners();
+    }
+  }
+
+  /// Helper to check if a store plugin ID is already installed.
+  bool isPluginInstalled(String pluginId) {
+    return _installedPlugins.any((p) => p.id == pluginId);
+  }
+}

gui/lib/models/store_plugin.dart

@@ -0,0 +1,51 @@
+// OpenROM — Universal ROM Compression Suite
+// M5 Dev | GPL v3
+
+class StorePlugin {
+  final String id;
+  final String name;
+  final String version;
+  final String author;
+  final String description;
+  final bool isVerified;
+  final String? downloadUrl;
+  final List<String> tags;
+
+  const StorePlugin({
+    required this.id,
+    required this.name,
+    required this.version,
+    required this.author,
+    required this.description,
+    this.isVerified = false,
+    this.downloadUrl,
+    this.tags = const [],
+  });
+
+  factory StorePlugin.fromJson(Map<String, dynamic> json) {
+    final rawTags = json['tags'] as List<dynamic>? ?? [];
+    return StorePlugin(
+      id: json['id'] as String? ?? '',
+      name: json['name'] as String? ?? '',
+      version: json['version'] as String? ?? '',
+      author: json['author'] as String? ?? '',
+      description: json['description'] as String? ?? '',
+      isVerified: json['isVerified'] as bool? ?? false,
+      downloadUrl: json['downloadUrl'] as String?,
+      tags: rawTags.map((e) => e.toString()).toList(),
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return {
+      'id': id,
+      'name': name,
+      'version': version,
+      'author': author,
+      'description': description,
+      'isVerified': isVerified,
+      if (downloadUrl != null) 'downloadUrl': downloadUrl,
+      'tags': tags,
+    };
+  }
+}