feat(tenancies-p3): webhook auto-create on signed Reservation Agreement + first-insert flip

- berth-tenancies.service.ts: autoCreatePendingTenancies(portId, interestId, opts)
  loops over interest_berths WHERE is_in_eoi_bundle=true and mints ONE
  pending tenancy per in-bundle berth. Wrapped in pg_advisory_xact_lock
  per port + idempotent skip when a (pending|active) tenancy already
  exists for the berth (webhook retry-safe). Each insert audit-logged
  + emits berth_tenancy:created socket event.
- createPending: same advisory-lock + tx pattern, additionally calls
  enableTenanciesModule(portId) so the FIRST manual tenancy in a port
  lazily flips tenancies_module_enabled=true (idempotent UPSERT, no-op
  on subsequent inserts).
- handleDocumentCompleted: branch on reservation_agreement completion
  gates on isTenanciesModuleEnabled, then calls autoCreatePendingTenancies
  with the just-committed signedFileId. Per design §"When disabled":
  stage advance + reservationDocStatus flip still fire when the module
  is off; only the tenancy mint is skipped.
- 5-case integration test covering bundle expansion, idempotent retry,
  empty-bundle no-op, missing-interest no-op, and the first-insert
  module-enable side effect.

Verified: tsc clean, 1485/1485 vitest (5 new cases).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/services/documents.service.ts

@@ -1660,6 +1660,36 @@ export async function handleDocumentCompleted(eventData: { documentId: string; p
     void import('@/lib/services/berth-rules-engine').then(({ evaluateRule }) =>
       evaluateRule('contract_signed', doc.interestId!, doc.portId, systemMeta),
     );
+
+    // Tenancies P3 — auto-create pending tenancies (one per in-bundle berth)
+    // when the module is enabled for this port. Gating is at the call site:
+    // disabled module = stage + docStatus updates still fire, only the
+    // tenancy mint is skipped (per docs/tenancies-design.md §"When disabled").
+    void (async () => {
+      try {
+        const { isTenanciesModuleEnabled } =
+          await import('@/lib/services/tenancies-module.service');
+        if (!(await isTenanciesModuleEnabled(doc.portId))) return;
+        const { autoCreatePendingTenancies } =
+          await import('@/lib/services/berth-tenancies.service');
+        // Re-read signedFileId from the post-commit row; the in-tx update
+        // above sets it, but doc was loaded before completion.
+        const fresh = await db.query.documents.findFirst({
+          where: eq(documents.id, doc.id),
+          columns: { signedFileId: true },
+        });
+        await autoCreatePendingTenancies(doc.portId, doc.interestId!, {
+          signedAt: new Date(),
+          sourceDocumentId: doc.id,
+          signedFileId: fresh?.signedFileId ?? null,
+        });
+      } catch (err) {
+        logger.error(
+          { err, documentId: doc.id, interestId: doc.interestId, portId: doc.portId },
+          'autoCreatePendingTenancies failed during reservation_agreement completion',
+        );
+      }
+    })();
   }
 
   // Update interest if contract type. Outcome flip to 'won' is a separate