0.22.3: the board runs on Bun in its image

The Docker image now runs the board on Bun 1.4.0 (Debian 12, same pandoc/WeasyPrint/poppler versions). The npm package still targets Node 24. serve exits on SIGTERM, so docker stop no longer waits 10 s.

Also since 0.22.2: watch account limit checks are serialized (#282), array values in structured pay amounts are rejected (#281), updates refuse links to board pages that do not exist (#280), timestamptz offsets with seconds parse (#279), the URL's sslmode no longer overrides the pool's SSL choice (#278), and merges deploy to dev2 (#277). Full diff: v0.22.2...v0.22.3