CI ran `yarn && yarn dev` with no committed yarn.lock, so every run resolved
the latest matching versions and dependency drift broke the pipeline in two
independent ways:
- select2 4.1.0 added engines.node ">=24" but the runner used node 22, so
`yarn install` failed outright on every pull request.
- webpack 5.108 removed lib/SizeFormatHelpers, which laravel-mix 6 still
requires, so `yarn dev` would have failed the build regardless of node.
Switch the workflow to `npm ci`, which installs the exact, known-good
versions already pinned in package-lock.json (select2 4.0.13, webpack
5.100.1) and is verified to build and lint cleanly. Pin the runner to node
24 via actions/setup-node so the toolchain is explicit rather than tracking
the runner default. Also pin select2 to ~4.0.13 in package.json so a future
`npm install` cannot pull the incompatible 4.1.0 back in.