chore(deps): remove unused npm-run-all dependency

Removes npm-run-all (and its transitive dep shell-quote) which is no
longer used - pnpm's native glob pattern handles parallel script
execution. Resolves GHAS dependabot alert #69 (shell-quote CVE).

Author: kmugEq

packages/extension/package.json

@@ -426,7 +426,6 @@
     "@vscode/test-cli": "^0.0.15",
     "@vscode/test-electron": "^3.0.0",
     "esbuild": "^0.28.1",
-    "npm-run-all": "^4.1.5",
     "tsx": "^4.22.4"
   }
 }