Package game as Electron desktop app

Custom app:// privileged protocol (standard, secure, fetch, stream) serves
the game so absolute /assets/ fetches and streamed mp3 loops work without
game code changes. Borderless windowed fullscreen, F11/F12/Ctrl+R/Ctrl+Shift+I
accelerators, single-instance lock, and an opt-in MS_VERIFY harness that
drives a run and dumps asset/audio diagnostics.

Pinned electron@40.10.2 + electron-builder@25.1.8 for Node 20 compatibility.
Builder allowlist ships only runtime content and excludes assets/raw.

package.json

@@ -0,0 +1,17 @@
+{
+  "name": "meatslicer",
+  "productName": "MeatSlicer",
+  "version": "0.1.0",
+  "private": true,
+  "description": "A Butcher's Descent - clear, harvest, descend.",
+  "main": "desktop/main.js",
+  "scripts": {
+    "start": "electron .",
+    "dist": "electron-builder --win zip",
+    "test": "node test/smoke.js"
+  },
+  "devDependencies": {
+    "electron": "^40.10.2",
+    "electron-builder": "^25.1.8"
+  }
+}