fix(desktop): restore Electron binary before macOS pack rename (salvage #38673)

electron-builder 26.8.x can stage an Electron.app without its
Contents/MacOS/Electron binary, then fail renaming it to Hermes:

    ENOENT: no such file or directory, rename .../MacOS/Electron -> .../MacOS/Hermes

This breaks `npm run pack` and the installer desktop stage before a
launchable Hermes.app exists.

- Point build.electronDist at the already-installed Electron dist so
  electron-builder reuses it instead of re-unpacking from cache.
- Add a darwin-only prebuilder patch that restores the missing main
  binary from the runtime dist before the rename. Idempotent (marker
  guard), soft-fails on shape mismatch, survives node_modules reinstall.

Co-authored-by: ChasLui <chaslui@outlook.com>

apps/desktop/package.json

@@ -20,6 +20,7 @@
     "start": "npm run build && electron .",
     "build": "node scripts/assert-root-install.cjs && node scripts/write-build-stamp.cjs && node scripts/stage-native-deps.cjs && tsc -b && vite build && npm run postbuild",
     "postbuild": "node scripts/assert-dist-built.cjs",
+    "prebuilder": "node scripts/patch-electron-builder-mac-binary.cjs",
     "builder": "cross-env NODE_OPTIONS=--max-old-space-size=16384 electron-builder",
     "pack": "npm run build && npm run builder -- --dir",
     "dist": "npm run build && npm run builder",
@@ -134,6 +135,7 @@
   },
   "build": {
     "electronVersion": "40.9.3",
+    "electronDist": "../../node_modules/electron/dist",
     "appId": "com.nousresearch.hermes",
     "productName": "Hermes",
     "executableName": "Hermes",