Release packaging: unsigned mac DMG build + install/security-bypass docs

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

package.json

@@ -19,7 +19,8 @@
     "mac": {
       "category": "public.app-category.music",
       "target": "dmg",
-      "icon": "build/icon.icns"
+      "icon": "build/icon.icns",
+      "identity": null
     },
     "files": [
       "main.js",