feat(hierarchy): audit event + outbox machinery (M4-1b-i, contract 1 §5.2)

- hierarchy_audit_events: append-only semantic events (actor, verb, target
  snapshot with root-first parent chain), deletion-safe linkage (no FK into
  class tables), CHECK-enforced verb/target-kind/transfer shape, unique
  idempotency key, generated-always seq for per-target ordering, causation
  self-FK RESTRICT; hierarchy_outbox: dedicated same-transaction outbox
  (unique event_id, status enum, claim-by-CAS lifecycle) — migration 0019
- gateway HierarchyAuditRepository: same-tx append with idempotent replay
  (canonical-JSON compare, jsonb key order independent), snapshot builder,
  per-target history, outbox claim/complete/release; HierarchyModule exposes
  no routes yet (command family lands in M4-1b-ii after contract 2 merges)
- dual-leg schema witnesses (PGlite + real PG) for every constraint above;
  repository §6.4 witnesses: atomic commit, rollback residue-free, replay,
  conflicting-key refusal, events survive target deletion, CAS races
- §6.3(a) route-inventory baseline: enumerates the AppModule route surface,
  pins zero hierarchy mutation routes until M4-1b-ii
- writer-coverage scan perimeter widened from <pkg>/src to the full package
  tree (S1 residual; widened set measured free of all trigger tokens)

packages/db/drizzle/meta/_journal.json

@@ -134,6 +134,13 @@
       "when": 1787862158838,
       "tag": "0018_clean_cobalt_man",
       "breakpoints": true
+    },
+    {
+      "idx": 19,
+      "version": "7",
+      "when": 1787880918208,
+      "tag": "0019_volatile_killraven",
+      "breakpoints": true
     }
   ]
 }