Use frozen frontend dependencies in CI

[Williangalvani]

fix #4083

I'd play with the frontend before merging, just in case

[github-actions]

Automated PR Review

0. Summary

• Verdict: LGTM

Adds --frozen-lockfile to bun install in both the CI workflow (.github/workflows/test-and-deploy.yml) and the production Docker build (core/Dockerfile) so installs match the committed core/frontend/bun.lockb exactly, and drops the stale bun.lockb entry from core/frontend/.gitignore (the file was already tracked, so the ignore rule was inert).

No further comments, nice job 👍

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