Upgrades all references of pgvector/pgvector from pg16 to pg18,
including docker-compose files and e2e testing environments.
Updates the development docker-compose to mount the postgres volume
at /var/lib/postgresql to align with pg18+ directory requirements.
Also adds `shrink-0` to WhatsNewDialog header and footer to resolve
a layout overflow glitch.
Emit transfer events when watcher reconciliation moves a book between libraries. Keep file-as-book and folder-as-book watcher paths consistent across Docker, direct runs, and delayed copy-delete moves.
Closes#386