chore(ci): TEMPORARY - install the unreleased webpack-dev-middleware

DO NOT MERGE THIS COMMIT. Revert it, and set the dependency back to a
released `^8.4.0`, once webpack-dev-middleware ships.

This branch needs what the published 8.3.0 does not have: `hot.protocol`
with this server's runtime in `client/webpack-dev-server/`, `onConnect`
with the request, `handleUpgrade`, `publishTo`, `hot.ws` and the `ws`
server handed out as `hot.implementation`. CI installs from the
registry, so without this `tsc` fails in the Build step and every job
behind it is cancelled.

This vendors a pack of webpack-dev-middleware `main` plus
webpack/webpack-dev-middleware#2472 (feat/finish-dev-server-migration).
The lockfile change is confined to that one dependency.

To undo, with the release out:

    git revert <this commit>
    npm install webpack-dev-middleware@^8.4.0

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UjuMAuk9o6UazjHzcAQCTA

Author: alexander-akait

package-lock.json

@@ -86,7 +86,7 @@
     "selfsigned": "^5.5.0",
     "serve-index": "^1.9.2",
     "tinyglobby": "^0.2.15",
-    "webpack-dev-middleware": "^8.0.3",
+    "webpack-dev-middleware": "file:vendor/webpack-dev-middleware.tgz",
     "ws": "^8.20.0"
   },
   "devDependencies": {