The AppView side of the PDS→AppView ingest path. Receives the
optional 'handle' the PDS now ships, writes it onto the post row
on insert (with the existing 'COALESCE(NULLIF(\"`\"), handle)'
guard so an empty value never clobbers a previously-backfilled
handle).
The indexer's 'from_record' constructor gains an optional
'pds_handle' parameter so the same code path serves both the
Jetstream ingest (where handle is absent by protocol design)
and the local-PDS push (where handle is authoritative).
Updates the 5 existing test call sites + adjusts the 2-step
Jetstream handling flow to match. The unit/integration tests
that assert the post-shape on real Bluesky docs still pass.
tomdebone