The Plex watch import inserted plex_states via per-row ORM add against a pre-read 'existing' set,
which is not safe when the enable call fires more than once while the multi-second import runs (the
toggle wasn't disabled during it): overlapping imports raced to INSERT the same (user_id, item_id)
rows and all but the first hit a UniqueViolation -> 500 (seen on prod). Rewrite the write path as a
chunked PostgreSQL UPSERT (on_conflict_do_update, rows de-duped by item_id) — idempotent and
concurrency-safe, Plex still wins on the intersection and Siftlode-only states are untouched.
Also disable the Settings toggle (and ignore its onChange) while a sync mutation is pending, so it
can't be fired repeatedly; adds a reusable 'disabled' prop to the Switch primitive.
5592f60e85