feat(preferences): add getAll method and IPC handler for retrieving all preferences

This commit introduces a new IPC channel and handler for fetching all user preferences at once, enhancing the efficiency of preference management. The PreferenceService is updated with a getAll method to retrieve all preferences from the memory cache, and the renderer-side PreferenceService is adjusted to support this new functionality. Additionally, type safety improvements are made across the preference handling code, ensuring better consistency and reducing potential errors.

src/main/data/PreferenceService.ts

@@ -273,6 +273,19 @@ export class PreferenceService {
     setInterval(cleanup, 30000)
   }
 
+  /**
+   * Get all preferences from memory cache
+   * Returns complete preference object for bulk operations
+   */
+  getAll(): PreferenceDefaultScopeType {
+    if (!this.initialized) {
+      logger.warn('Preference cache not initialized, returning defaults')
+      return DefaultPreferences.default
+    }
+
+    return { ...this.cache }
+  }
+
   /**
    * Get all current subscriptions (for debugging)
    */