v0.3.3 — the app and the audit worker run on Bun

Both processes in the container now run on Bun (#337): the Next standalone server (bun server.js) and the audit worker (bun worker/index.ts). Dependencies are installed by Bun from a lockfile migrated from npm with every version unchanged, and Next builds on Bun. The runtime image stays on Playwright 1.60 (Chromium, pandoc, ffmpeg) with the Bun binary added.

On dev2 the container uses about 440 MiB where it used about 680 MiB on Node, with the same latency and no errors over a 30-minute watch. Nothing user-facing changes.