feat: implement dynamic theme palette selection

- Introduced a new feature allowing users to select from multiple accent color palettes for buttons, cards, and chat bubbles.
- Added `AppThemePalette` provider to manage the current theme palette and persist user selections.
- Updated the `AppTheme` class to utilize the selected palette for light and dark themes, enhancing visual customization.
- Enhanced the `AppCustomizationPage` to include a palette selector, improving user experience and personalization options.
- Updated localization files to support new palette selection UI elements in multiple languages.

lib/core/persistence/persistence_keys.dart

@@ -18,6 +18,7 @@ final class PreferenceKeys {
   static const String rememberCredentials = 'remember_credentials';
   static const String activeServerId = 'active_server_id';
   static const String themeMode = 'theme_mode';
+  static const String themePalette = 'theme_palette_v1';
   static const String localeCode = 'locale_code_v1';
   static const String onboardingSeen = 'onboarding_seen_v1';
   static const String reviewerMode = 'reviewer_mode_v1';

lib/core/persistence/persistence_migrator.dart

@@ -89,6 +89,7 @@ class PersistenceMigrator {
     copyBool(PreferenceKeys.rememberCredentials);
     copyString(PreferenceKeys.activeServerId);
     copyString(PreferenceKeys.themeMode);
+    copyString(PreferenceKeys.themePalette);
     copyString(PreferenceKeys.localeCode);
     copyBool(PreferenceKeys.onboardingSeen);
     copyBool(PreferenceKeys.reviewerMode);
@@ -194,6 +195,7 @@ class PersistenceMigrator {
       PreferenceKeys.rememberCredentials,
       PreferenceKeys.activeServerId,
       PreferenceKeys.themeMode,
+      PreferenceKeys.themePalette,
       PreferenceKeys.localeCode,
       PreferenceKeys.onboardingSeen,
       PreferenceKeys.reviewerMode,

lib/core/providers/app_providers.dart

@@ -23,6 +23,8 @@ import '../services/optimized_storage_service.dart';
 import '../services/socket_service.dart';
 import '../utils/debug_logger.dart';
 import '../models/socket_event.dart';
+import '../../shared/theme/color_palettes.dart';
+import '../../shared/theme/app_theme.dart';
 
 part 'app_providers.g.dart';
 
@@ -78,6 +80,42 @@ class AppThemeMode extends _$AppThemeMode {
   }
 }
 
+@Riverpod(keepAlive: true)
+class AppThemePalette extends _$AppThemePalette {
+  late final OptimizedStorageService _storage;
+
+  @override
+  AppColorPalette build() {
+    _storage = ref.watch(optimizedStorageServiceProvider);
+    final storedId = _storage.getThemePaletteId();
+    return AppColorPalettes.byId(storedId);
+  }
+
+  Future<void> setPalette(String paletteId) async {
+    final palette = AppColorPalettes.byId(paletteId);
+    state = palette;
+    await _storage.setThemePaletteId(palette.id);
+  }
+}
+
+@Riverpod(keepAlive: true)
+class AppLightTheme extends _$AppLightTheme {
+  @override
+  ThemeData build() {
+    final palette = ref.watch(appThemePaletteProvider);
+    return AppTheme.light(palette);
+  }
+}
+
+@Riverpod(keepAlive: true)
+class AppDarkTheme extends _$AppDarkTheme {
+  @override
+  ThemeData build() {
+    final palette = ref.watch(appThemePaletteProvider);
+    return AppTheme.dark(palette);
+  }
+}
+
 // Locale provider
 @Riverpod(keepAlive: true)
 class AppLocale extends _$AppLocale {

lib/core/services/enhanced_accessibility_service.dart

@@ -2,7 +2,7 @@ import 'dart:math' as math;
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/semantics.dart';
-import '../../shared/theme/app_theme.dart';
+import '../../shared/theme/color_palettes.dart';
 import '../../shared/theme/theme_extensions.dart';
 
 /// Enhanced accessibility service for WCAG 2.2 AA compliance
@@ -349,9 +349,7 @@ class EnhancedAccessibilityService {
     return BoxDecoration(
       border: hasFocus
           ? Border.all(
-              color:
-                  focusColor ??
-                  AppTheme.brandPrimary, // Brand primary as fallback
+              color: focusColor ?? AppColorPalettes.auroraViolet.light.primary,
               width: borderWidth,
             )
           : null,

lib/core/services/optimized_storage_service.dart

@@ -35,6 +35,7 @@ class OptimizedStorageService {
   static const String _rememberCredentialsKey =
       PreferenceKeys.rememberCredentials;
   static const String _themeModeKey = PreferenceKeys.themeMode;
+  static const String _themePaletteKey = PreferenceKeys.themePalette;
   static const String _localeCodeKey = PreferenceKeys.localeCode;
   static const String _localConversationsKey = HiveStoreKeys.localConversations;
   static const String _onboardingSeenKey = PreferenceKeys.onboardingSeen;
@@ -261,6 +262,14 @@ class OptimizedStorageService {
     await _preferencesBox.put(_themeModeKey, mode);
   }
 
+  String? getThemePaletteId() {
+    return _preferencesBox.get(_themePaletteKey) as String?;
+  }
+
+  Future<void> setThemePaletteId(String paletteId) async {
+    await _preferencesBox.put(_themePaletteKey, paletteId);
+  }
+
   String? getLocaleCode() {
     return _preferencesBox.get(_localeCodeKey) as String?;
   }