The ER diagram and notes predated migrations 002-006. Brought them to
code truth:
- add summary_actions (002), user_identities (004), video_connections
(005) with real columns/constraints; rename token_secret_ref ->
token_ref to match migration 005.
- add users.auto_summarize and videos.summarize_requested (006).
- note FORCE RLS coverage and sink_deliveries' EXISTS-derived policy
(003); user_identities NOT RLS'd.
- mark AI_CREDENTIAL and SUBSCRIPTION as planned (no table exists; only
videos.subscription_id, no FK).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>