Add offline mode support with PIN configuration and management

- Introduce `OfflinePinSetup` component for users to configure secure offline access.
- Add new `AIUsageContext` and extend `OfflineProvider` for offline-related state management.
- Implement offline login functionality in `electron/main.ts` with PIN verification and fallback support.
- Enhance IPC handlers to manage offline mode data, PIN setup, and synchronization.
- Update localization files (`en.json`, `fr.json`) with offline mode and PIN-related strings.
- Add `bcrypt` and `@types/bcrypt` dependencies for secure PIN hashing and validation.
- Refactor login and session management to handle offline mode scenarios with improved error handling and flow.

electron.d.ts

@@ -36,6 +36,13 @@ export interface IElectronAPI {
 
   // Database initialization (shortcut for convenience)
   dbInitialize: (userId: string, encryptionKey: string) => Promise<boolean>;
+
+  // Offline mode management
+  offlinePinSet: (pin: string) => Promise<{ success: boolean; error?: string }>;
+  offlinePinVerify: (pin: string) => Promise<{ success: boolean; userId?: string; error?: string }>;
+  offlineModeSet: (enabled: boolean, syncInterval?: number) => Promise<{ success: boolean }>;
+  offlineModeGet: () => Promise<{ enabled: boolean; syncInterval: number; hasPin: boolean }>;
+  offlineSyncCheck: () => Promise<{ shouldSync: boolean; daysSinceSync?: number; syncInterval?: number }>;
 }
 
 declare global {