Feature: Add and implement i18n support for theme settings in German and English, refactor AppSettings to DesignSettings, and improve settings UI structure.

finlog_app/app/lib/core/i18n/translations.g.dart

@@ -4,9 +4,9 @@
 /// To regenerate, run: `dart run slang`
 ///
 /// Locales: 2
-/// Strings: 126 (63 per locale)
+/// Strings: 132 (66 per locale)
 ///
-/// Built on 2025-09-27 at 12:19 UTC
+/// Built on 2025-09-27 at 12:40 UTC
 
 // coverage:ignore-file
 // ignore_for_file: type=lint, unused_import

finlog_app/app/lib/core/i18n/translations_de.g.dart

@@ -98,6 +98,7 @@ class _TranslationsAppDe implements TranslationsAppEn {
 	@override String get tooltipCollapseRail => 'Leiste verkleinern';
 	@override String get tooltipExpandRail => 'Leiste erweitern';
 	@override String get drawerSettings => 'Einstellungen';
+	@override late final _TranslationsAppSettingsDe settings = _TranslationsAppSettingsDe._(_root);
 }
 
 // Path: settings
@@ -131,6 +132,16 @@ class _TranslationsFeaturesDe implements TranslationsFeaturesEn {
 	@override late final _TranslationsFeaturesReportsDe reports = _TranslationsFeaturesReportsDe._(_root);
 }
 
+// Path: app.settings
+class _TranslationsAppSettingsDe implements TranslationsAppSettingsEn {
+	_TranslationsAppSettingsDe._(this._root);
+
+	final TranslationsDe _root; // ignore: unused_field
+
+	// Translations
+	@override late final _TranslationsAppSettingsThemeDe theme = _TranslationsAppSettingsThemeDe._(_root);
+}
+
 // Path: settings.sections
 class _TranslationsSettingsSectionsDe implements TranslationsSettingsSectionsEn {
 	_TranslationsSettingsSectionsDe._(this._root);
@@ -281,6 +292,18 @@ class _TranslationsFeaturesReportsDe implements TranslationsFeaturesReportsEn {
 	@override String get description => 'Statistiken von Ausgaben';
 }
 
+// Path: app.settings.theme
+class _TranslationsAppSettingsThemeDe implements TranslationsAppSettingsThemeEn {
+	_TranslationsAppSettingsThemeDe._(this._root);
+
+	final TranslationsDe _root; // ignore: unused_field
+
+	// Translations
+	@override String get system => 'System';
+	@override String get light => 'Hell';
+	@override String get dark => 'Dunkel';
+}
+
 /// Flat map(s) containing all translations.
 /// Only for edge cases! For simple maps, use the map function of this library.
 extension on TranslationsDe {
@@ -306,6 +329,9 @@ extension on TranslationsDe {
 			case 'app.tooltipCollapseRail': return 'Leiste verkleinern';
 			case 'app.tooltipExpandRail': return 'Leiste erweitern';
 			case 'app.drawerSettings': return 'Einstellungen';
+			case 'app.settings.theme.system': return 'System';
+			case 'app.settings.theme.light': return 'Hell';
+			case 'app.settings.theme.dark': return 'Dunkel';
 			case 'settings.title': return 'Einstellungen';
 			case 'settings.sections.account': return 'Konto & Daten';
 			case 'settings.sections.app': return 'App';

finlog_app/app/lib/core/i18n/translations_en.g.dart

@@ -142,6 +142,8 @@ class TranslationsAppEn {
 
 	/// en: 'Settings'
 	String get drawerSettings => 'Settings';
+
+	late final TranslationsAppSettingsEn settings = TranslationsAppSettingsEn._(_root);
 }
 
 // Path: settings
@@ -178,6 +180,16 @@ class TranslationsFeaturesEn {
 	late final TranslationsFeaturesReportsEn reports = TranslationsFeaturesReportsEn._(_root);
 }
 
+// Path: app.settings
+class TranslationsAppSettingsEn {
+	TranslationsAppSettingsEn._(this._root);
+
+	final Translations _root; // ignore: unused_field
+
+	// Translations
+	late final TranslationsAppSettingsThemeEn theme = TranslationsAppSettingsThemeEn._(_root);
+}
+
 // Path: settings.sections
 class TranslationsSettingsSectionsEn {
 	TranslationsSettingsSectionsEn._(this._root);
@@ -412,6 +424,24 @@ class TranslationsFeaturesReportsEn {
 	String get description => 'Statistics of expenses';
 }
 
+// Path: app.settings.theme
+class TranslationsAppSettingsThemeEn {
+	TranslationsAppSettingsThemeEn._(this._root);
+
+	final Translations _root; // ignore: unused_field
+
+	// Translations
+
+	/// en: 'System'
+	String get system => 'System';
+
+	/// en: 'Light'
+	String get light => 'Light';
+
+	/// en: 'Dark'
+	String get dark => 'Dark';
+}
+
 /// Flat map(s) containing all translations.
 /// Only for edge cases! For simple maps, use the map function of this library.
 extension on Translations {
@@ -437,6 +467,9 @@ extension on Translations {
 			case 'app.tooltipCollapseRail': return 'Collapse Rail';
 			case 'app.tooltipExpandRail': return 'Expand Rail';
 			case 'app.drawerSettings': return 'Settings';
+			case 'app.settings.theme.system': return 'System';
+			case 'app.settings.theme.light': return 'Light';
+			case 'app.settings.theme.dark': return 'Dark';
 			case 'settings.title': return 'Settings';
 			case 'settings.sections.account': return 'Account & Data';
 			case 'settings.sections.app': return 'App';