feat: implement auto-update functionality with GitHub integration

- Added AutoUpdater class to manage update checks and downloads.
- Integrated auto-updater in the main process after the main window is created.
- Enhanced preload script to expose update-related IPC channels.
- Created UpdateDialog component to handle user interactions for updates.
- Implemented state management for update status using Pinia store.
- Added localization support for update messages in multiple languages.
- Documented auto-update configuration steps for private GitHub repositories.
- Created .env.example for GitHub token configuration.

.env.example

@@ -0,0 +1,6 @@
+# GitHub Personal Access Token for private repository access
+# Required for auto-updates from private repositories
+GH_TOKEN=
+
+# For private repositories, you might also need:
+# GITHUB_TOKEN= # Alternative token name that some tools might use