XP JOURNAL APPEND-ONLY + EVENT-ONCE

One economic event writes one journal row — the journal is append-only and a replayed event is a no-op.

044 migration: trigger refuses UPDATE/DELETE; partial UNIQUE (payer, kind, ref); both appendXp paths no-op replays; players.xp re-derived

packages/decisions + worker suites (event-once in store code); migration 044

DB-migration behavior not executable in this environment (Docker-gated)