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.

tsconfig.electron.json

@@ -0,0 +1,18 @@
+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "outDir": "electron",
+    "rootDir": "electron",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "resolveJsonModule": true,
+    "declaration": false,
+    "sourceMap": false
+  },
+  "include": ["electron/**/*.ts"],
+  "exclude": ["node_modules", "dist", "src"]
+}