Deploy on DigitalOcean App Platform (GitHub-source build) + consolidate audit-fixes

Deploy config:
- .do/app.yaml: build the Dockerfile directly from GitHub (deploy_on_push) instead
  of a pre-built DOCR image; NEXT_PUBLIC_* set RUN_AND_BUILD_TIME with the
  propertymanagement.network domain so they bake into the client bundle; add
  custom domains block (apex + www); wire Sentry DSN (server + browser).

Included pending work from the audit-fixes branch:
- AI provider abstraction (OpenAI/Anthropic, admin-selectable; Anthropic default)
- Per-landlord e-signature (DocuSign OAuth + Dropbox Sign) + migration 0010
- Outbound webhooks / Zapier integration
- PayPal removal (Stripe-only billing)
- Storage hardening (fail-loud when Spaces unconfigured), security fixes

Verified: full production Docker build (same build-args as DO) passes clean.

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

package.json

@@ -14,6 +14,7 @@
     "db:studio": "drizzle-kit studio"
   },
   "dependencies": {
+    "@anthropic-ai/sdk": "^0.110.0",
     "@aws-sdk/client-s3": "^3.1077.0",
     "@aws-sdk/s3-request-presigner": "^3.1078.0",
     "@fullcalendar/daygrid": "^6.1.21",
@@ -22,6 +23,7 @@
     "@fullcalendar/react": "^6.1.21",
     "@fullcalendar/timegrid": "^6.1.21",
     "@radix-ui/react-switch": "^1.2.6",
+    "@sentry/nextjs": "^10.63.0",
     "@types/papaparse": "^5.5.2",
     "better-auth": "^1.6.20",
     "clsx": "^2.1.1",