feat: implement API-first settings management and description history tracking

- Migrated settings persistence from localStorage to an API-first approach, ensuring consistency between Electron and web modes.
- Introduced `useSettingsSync` hook for automatic synchronization of settings to the server with debouncing.
- Enhanced feature update logic to track description changes with a history, allowing for better management of feature descriptions.
- Updated various components and services to utilize the new settings structure and description history functionality.
- Removed persist middleware from Zustand store, streamlining state management and improving performance.

apps/ui/src/lib/electron.ts

@@ -459,7 +459,9 @@ export interface FeaturesAPI {
   update: (
     projectPath: string,
     featureId: string,
-    updates: Partial<Feature>
+    updates: Partial<Feature>,
+    descriptionHistorySource?: 'enhance' | 'edit',
+    enhancementMode?: 'improve' | 'technical' | 'simplify' | 'acceptance'
   ) => Promise<{ success: boolean; feature?: Feature; error?: string }>;
   delete: (projectPath: string, featureId: string) => Promise<{ success: boolean; error?: string }>;
   getAgentOutput: (