fix(audit-tier-1): timeouts, lifecycle, per-port Documenso, FK constraints

Closes the second wave of HIGH-priority audit findings:

* fetchWithTimeout helper (new src/lib/fetch-with-timeout.ts) wraps
  Documenso, OCR, currency, Umami, IMAP, etc. — a hung upstream can
  no longer pin a worker concurrency slot indefinitely.  OpenAI client
  passes timeout: 30_000.  ImapFlow gets socket / greeting / connection
  timeouts.
* SIGTERM / SIGINT handler in src/server.ts drains in-flight HTTP,
  closes Socket.io, and disconnects Redis before exit; compose
  stop_grace_period bumped to 30s.  Adds closeSocketServer() helper.
* env.ts gains zod-validated PORT and MULTI_NODE_DEPLOYMENT, and
  filesystem.ts now reads from env (a typo can no longer silently
  disable the multi-node guard).
* Per-port Documenso template + recipient IDs land in system_settings
  with env fallback (PortDocumensoConfig now exposes eoiTemplateId,
  clientRecipientId, developerRecipientId, approvalRecipientId).
  document-templates.ts uses the per-port config and threads portId
  into documensoGenerateFromTemplate().
* Migration 0042 wires the eleven HIGH-tier missing FK constraints
  (documents/files/interests/reminders/berth_waiting_list/
  form_submissions) plus polymorphic CHECK round 2
  (yacht_ownership_history.owner_type, document_sends.document_kind),
  invoices.billing_entity_id NOT EMPTY, and clients.merged_into self-FK.
  Drizzle schema columns updated to .references(...) where possible
  so the misleading "FK wired in relations.ts" comments are gone.

Test status: 1168/1168 vitest, tsc clean.

Refs: docs/audit-comprehensive-2026-05-05.md HIGH §§5,6,7,8,9,10 +
MED §§14,15,16,18.

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

src/lib/services/document-templates.ts

@@ -25,6 +25,7 @@ import {
   generateDocumentFromTemplate as documensoGenerateFromTemplate,
 } from '@/lib/services/documenso-client';
 import { buildDocumensoPayload, getPortEoiSigners } from '@/lib/services/documenso-payload';
+import { getPortDocumensoConfig } from '@/lib/services/port-config';
 import { generateEoiPdfFromTemplate } from '@/lib/pdf/fill-eoi-form';
 import { MERGE_FIELDS, type MergeFieldCatalog } from '@/lib/templates/merge-fields';
 import { buildEoiContext } from '@/lib/services/eoi-context';
@@ -882,12 +883,17 @@ async function generateAndSignViaDocumensoTemplate(
 
   const eoiContext = await buildEoiContext(context.interestId, portId);
   const signers = await getPortEoiSigners(portId);
+  // Per-port Documenso template + recipient IDs (with env fallback). Each
+  // tenant pointing at its own Documenso instance has different numeric
+  // template + recipient IDs, so a global env-only setup limits the
+  // platform to one Documenso instance per CRM process.
+  const docCfg = await getPortDocumensoConfig(portId);
 
   const payload = buildDocumensoPayload(eoiContext, {
     interestId: context.interestId,
-    clientRecipientId: env.DOCUMENSO_CLIENT_RECIPIENT_ID,
-    developerRecipientId: env.DOCUMENSO_DEVELOPER_RECIPIENT_ID,
-    approvalRecipientId: env.DOCUMENSO_APPROVAL_RECIPIENT_ID,
+    clientRecipientId: docCfg.clientRecipientId,
+    developerRecipientId: docCfg.developerRecipientId,
+    approvalRecipientId: docCfg.approvalRecipientId,
     developerName: signers.developer.name,
     developerEmail: signers.developer.email,
     approverName: signers.approver.name,
@@ -896,8 +902,9 @@ async function generateAndSignViaDocumensoTemplate(
   });
 
   const documensoDoc = await documensoGenerateFromTemplate(
-    env.DOCUMENSO_TEMPLATE_ID_EOI,
+    docCfg.eoiTemplateId,
     payload as unknown as Record<string, unknown>,
+    portId,
   );
 
   // Record a documents row referencing the Documenso document. No local file -