Fix game status: use DB index as authority for status and playerTwo
The join endpoint can't write to player one's PDS repo (ATProto constraint),
so the PDS game record never gets updated with playerTwo or status='active'.
The DB index is the source of truth for these fields since the join endpoint
controls them. PDS remains authoritative for scores and winner.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>