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>

app/global-error.tsx

@@ -1,5 +1,6 @@
 "use client"
 
+import * as Sentry from "@sentry/nextjs"
 import { useEffect } from "react"
 
 export default function GlobalError({
@@ -10,6 +11,7 @@ export default function GlobalError({
   reset: () => void
 }) {
   useEffect(() => {
+    Sentry.captureException(error)
     console.error(error)
   }, [error])