Consolidate audit-fixes branch: webhooks, integrations, and deploy hardening

Batch commit of the pending working tree on security/audit-fixes-2026-07.
Major areas:
- Outbound webhooks / Zapier: schema + signed delivery with retries, public
  v1 API (REST-hook subscribe/unsubscribe), settings UI, cron drain.
- Deploy hardening: email via SMTP2GO (Resend fully removed), verified DB TLS
  (DATABASE_SSL=require + DATABASE_CA), storage fails loud in production when
  Spaces is unconfigured instead of silently using ephemeral disk.
- Integrations & features (concurrent work): accounting (QuickBooks/Xero),
  e-signature (DocuSign/Dropbox Sign), PayPal, geocoding/maps, onboarding,
  expanded legal pages.
- DB migrations 0006–0009.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -23,6 +23,7 @@
 # misc
 .DS_Store
 *.pem
+*.crt
 
 # local file storage (uploaded documents/photos)
 /storage
@@ -38,18 +39,10 @@ yarn-error.log*
 !.env.example
 !.env.production.example
 
-# Legacy Supabase check script — contains a hardcoded service_role key.
-# Excluded from version control; rotate that key and delete this file.
-supabase/verify.mjs
-
-# vercel
-.vercel
-
 # typescript
 *.tsbuildinfo
 next-env.d.ts
 .env.local
 DOCS/
 
-.vercel
 .env*.local