Row locks on SQLite / D1: refuse in the type, document the replacement #85

Signal

forUpdate / forShare exist for Postgres. SQLite and D1 have no row locks. We want:

• forUpdate absent from the type of a D1 or SQLite query (capability-driven), not a run-time error.
• Documented replacement patterns: a conditional update as a claim (UPDATE … WHERE status = 'pending' RETURNING), and single-writer Durable Objects.

Why (MyRemotely)

• 29 FOR UPDATE sites today. Examples are tour slot booking, passcode allocation and RSVP races. Each one needs a D1 or DO form during the move.
• A refusal in the type shows us every site that needs a redesign.

Part of #52: the CAFE-stack roadmap signal from MyRemotely. This shows the direction we want, and it is not a demand. We can send a PR if you accept the idea.