Migrate app from Tauri to Electron

Replace the Tauri/sidecar architecture with an Electron main process. Adds an electron/ directory (main, preload, handlers, core integrations for @xmcl/*), electron-builder.yml, TypeScript electron config and declarations, and updated IPC utilities (ipc.ts) so frontend uses ipcRenderer/ipcMain. Removes Tauri sidecar and src-tauri artifacts, deletes sidecar sources and keys, updates .gitignore, VSCode recommendations, package scripts and icons, and updates documentation (README, AGENTS, DEV) and frontend stores/apis to reflect the Electron-based architecture and config/auth persistence changes.

.gitignore

@@ -10,6 +10,7 @@ lerna-debug.log*
 node_modules
 dist
 dist-ssr
+dist-electron
 *.local
 
 # Editor directories and files
@@ -22,3 +23,7 @@ dist-ssr
 *.njsproj
 *.sln
 *.sw?
+
+# Electron
+electron/*.js
+electron/*.d.ts