feat(desktop-client): tighten window mode switching and add win/linux package scripts

- Track each window's renderer mode in a WeakMap (and fall back to
  parsing ?window= from the URL) so retireInactiveAppWindows can
  destroy stale login/main/settings windows when we switch modes,
  not just the previous one of the canonical pair.
- Replace closeWindowAfterIpcReturn with retireWindowAfterIpcReturn
  (hides immediately, then destroys instead of close()) so the IPC
  reply still reaches the caller before teardown.
- Add waitForWindowReady() with a 1.2s ceiling and call it from
  revealWindow so we don't show a half-loaded shell while
  switchWindowMode is running. Pass the source window from the IPC
  event into switchWindowMode so the closing target is the actual
  caller, not a guess based on mode.
- Silence console.* and skip the observed-fetch install in packaged
  runtime, and only auto-openDevTools in dev.
- Eagerly import LoginView in App.vue instead of defineAsyncComponent
  to remove the boot flash on the login window.
- package.json: prefix package:* with `pnpm run build` and add
  package:win and package:linux for parity.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/desktop-client/package.json

@@ -13,7 +13,9 @@
   "scripts": {
     "dev": "unset ELECTRON_RUN_AS_NODE && electron-vite dev --inspect=9229",
     "build": "electron-vite build",
-    "package:mac": "electron-builder --mac --arm64",
+    "package:mac": "pnpm run build && electron-builder --mac --arm64,universal",
+    "package:win": "pnpm run build && electron-builder --win --x64",
+    "package:linux": "pnpm run build && electron-builder --linux --x64,arm64",
     "sign:setup": "bash scripts/sign-setup.sh",
     "sign:mac": "bash scripts/sign-mac.sh",
     "test": "vitest run",