fix(frontend): remove unused MSW browser worker (#6859)

The frontend uses MSW only through its Node test interceptor, but the unused browser worker requires synchronization after dependency updates and currently breaks make verify.

Remove the unused asset, worker-directory configuration, and freshness checks while preserving Node MSW tests and the separate PWA worker. Update tooling descriptions to match.

Fixes #6858

frontend/package.json

@@ -115,10 +115,5 @@
     "tree-sitter-json": false,
     "msw": false,
     "esbuild": false
-  },
-  "msw": {
-    "workerDirectory": [
-      "public"
-    ]
   }
 }