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/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?;
   }