- Add AI.VectorCaptionOnIndex UI setting with rollback on API error
- Backend: persist/read vector_caption_on_index via AppSettings
- Expose set_vector_caption_on_index via health route and clientOps API
- Wire is_vector_caption_on_index_enabled() into config + env vars
- Update vector_indexer to honour the caption-on-index flag
- Add tests: settings backend, health routes, vector indexer video alignment
- Extend grid_scope_switch_cache test coverage