fix: normalize repository.url in npm placeholder package (#423)

Add git+ prefix to repository URL to match npm registry convention
and suppress npm publish warning.

🖥️ IDE: [Cursor](https://cursor.sh)
🔌 Extension: [Claude Code](https://claude.ai/download)


Model-Raw: claude-opus-4-6-20250415

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: nullvariant

packages/git-id-switcher-npm/package.json

@@ -8,7 +8,7 @@
   "homepage": "https://marketplace.visualstudio.com/items?itemName=nullvariant.git-id-switcher",
   "repository": {
     "type": "git",
-    "url": "https://github.com/nullvariant/nullvariant-vscode-extensions.git",
+    "url": "git+https://github.com/nullvariant/nullvariant-vscode-extensions.git",
     "directory": "packages/git-id-switcher-npm"
   },
   "keywords": [