Record a play event from an authenticated player

Reports a play event from an authenticated player. Events are de-duplicated per UTC day per session, so resuming from pause or replaying a region within one session counts once. `download` and `embed_resolved` are NOT accepted on this route — those are recorded by the API automatically to keep the counts authoritative.

curl -X POST "https://example.com/assets/497f6eca-6276-4993-bfeb-53cbbbba6f08/access-activity" \  -H "Content-Type: application/json" \  -d '{    "eventType": "play_started",    "visibility": "creator"  }'