Delete My Account

Delete the calling user's account and personal data.

Sequence:

1. Resolve user from Clerk session
2. Capture clerk_user_id BEFORE we touch the row (we'll need it for Clerk revocation after the local delete)
3. Anonymize PII fields — this satisfies the privacy obligation even if subsequent steps fail
4. Wipe PII-heavy child tables explicitly (the ones that don't have CASCADE on FK or that hold standalone PII)
5. Hard delete the users row (CASCADE handles most child tables)
6. Revoke from Clerk
7. Return confirmation

Returns: 200 {ok: true, anonymized: true, hard_deleted: bool, clerk_revoked: bool} 410 if account is already deleted (idempotent re-delete)