refactor(settings): make expansion tiles mutually exclusive

- Convert _SettingsView from StatelessWidget to StatefulWidget
- Add ExpansionTileController for each expansion tile
- Implement onExpansionChanged to collapse other tiles when one is expanded
- Ensure proper disposal of controllers

Author: fulleni

lib/settings/view/settings_page.dart

@@ -27,9 +27,30 @@ class SettingsPage extends StatelessWidget {
   }
 }
 
-class _SettingsView extends StatelessWidget {
+class _SettingsView extends StatefulWidget {
   const _SettingsView();
 
+  @override
+  State<_SettingsView> createState() => _SettingsViewState();
+}
+
+class _SettingsViewState extends State<_SettingsView> {
+  late List<ExpansionTileController> _mainTileControllers;
+
+  @override
+  void initState() {
+    super.initState();
+    _mainTileControllers = List.generate(2, (index) => ExpansionTileController());
+  }
+
+  @override
+  void dispose() {
+    for (final controller in _mainTileControllers) {
+      controller.dispose();
+    }
+    super.dispose();
+  }
+
   @override
   Widget build(BuildContext context) {
     final l10n = AppLocalizationsX(context).l10n;
@@ -112,7 +133,17 @@ class _SettingsView extends StatelessWidget {
               padding: const EdgeInsets.all(AppSpacing.lg),
               children: [
                 ExpansionTile(
+                  controller: _mainTileControllers[0],
                   title: Text(l10n.appearanceSettingsLabel),
+                  onExpansionChanged: (isExpanded) {
+                    if (isExpanded) {
+                      for (var i = 0; i < _mainTileControllers.length; i++) {
+                        if (i != 0) {
+                          _mainTileControllers[i].collapse();
+                        }
+                      }
+                    }
+                  },
                   childrenPadding: const EdgeInsets.symmetric(
                     horizontal: AppSpacing.xxl,
                   ),
@@ -263,7 +294,17 @@ class _SettingsView extends StatelessWidget {
                   ],
                 ),
                 ExpansionTile(
+                  controller: _mainTileControllers[1],
                   title: Text(l10n.languageSettingsLabel),
+                  onExpansionChanged: (isExpanded) {
+                    if (isExpanded) {
+                      for (var i = 0; i < _mainTileControllers.length; i++) {
+                        if (i != 1) {
+                          _mainTileControllers[i].collapse();
+                        }
+                      }
+                    }
+                  },
                   childrenPadding: const EdgeInsets.symmetric(
                     horizontal: AppSpacing.xxl,
                   ),