refactor: centralize platform-specific behavior in platform services

- Add platform-specific capability methods to PlatformService interface:
  - getExportInstructions()
  - getExportSuccessMessage()
  - needsSecondaryDownloadLink()
  - needsDownloadCleanup()

- Update platform service implementations:
  - WebPlatformService: Implement web-specific export behavior
  - CapacitorPlatformService: Implement mobile-specific export behavior
  - ElectronPlatformService: Add placeholder for export functionality
  - PyWebViewPlatformService: Add placeholder for export functionality

- Refactor DataExportSection component:
  - Remove direct platform checks (isWeb, isCapacitor, etc.)
  - Use platform service capabilities for UI behavior
  - Improve error handling and logging
  - Add proper cleanup for web platform downloads

- Update PlatformServiceFactory:
  - Make getInstance() async to support dynamic imports
  - Improve platform service initialization

- Fix code style and documentation:
  - Update JSDoc comments
  - Fix string quotes consistency
  - Add proper error handling
  - Improve logging messages

- Update Vite config:
  - Add all Capacitor dependencies to external list
  - Ensure consistent handling across platforms

src/services/platforms/ElectronPlatformService.ts

@@ -5,7 +5,7 @@ import { logger } from "../../utils/logger";
  * Platform service implementation for Electron (desktop) platform.
  * Note: This is a placeholder implementation with most methods currently unimplemented.
  * Implements the PlatformService interface but throws "Not implemented" errors for most operations.
- * 
+ *
  * @remarks
  * This service is intended for desktop application functionality through Electron.
  * Future implementations should provide:
@@ -121,4 +121,16 @@ export class ElectronPlatformService implements PlatformService {
     logger.error("handleDeepLink not implemented in Electron platform");
     throw new Error("Not implemented");
   }
+
+  /**
+   * Exports a database blob to a file.
+   * @param _blob - The database blob to export
+   * @param _fileName - The name of the file to save
+   * @throws Error with "Not implemented" message
+   * @todo Implement file export using Electron's file system API
+   */
+  async exportDatabase(_blob: Blob, _fileName: string): Promise<void> {
+    logger.error("exportDatabase not implemented in Electron platform");
+    throw new Error("Not implemented");
+  }
 }