Monitors all file-backed databases for changes by polling PRAGMA data_version
via a dedicated sqlite3 connection per database. Detected changes update
datasette._database_updated with the time.monotonic() timestamp. Watchers
start on ASGI startup and are cancelled on shutdown. The /-/databases endpoint
now includes a "last_updated" field for each database.
https://claude.ai/code/session_018W3THaecoPG4K8pFuthz62
