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/robots.ts

@@ -0,0 +1,44 @@
+import type { MetadataRoute } from "next"
+
+export default function robots(): MetadataRoute.Robots {
+  const base = process.env.NEXT_PUBLIC_APP_URL ?? "https://propertymanagement.network"
+
+  return {
+    rules: {
+      userAgent: "*",
+      allow: "/",
+      // Private/app areas. Mirrors PROTECTED_PATHS in proxy.ts, plus the API
+      // surface and the token-gated tenant portal (both private but enforced
+      // outside the cookie proxy). `/tenant-portal/` keeps the trailing slash so
+      // it doesn't also block the indexable `/tenant-portal-info` marketing page.
+      disallow: [
+        "/dashboard",
+        "/admin",
+        "/api/",
+        "/settings",
+        "/onboarding",
+        "/team",
+        "/tenant-portal/",
+        "/calendar",
+        "/inspections",
+        "/vendors",
+        "/reports",
+        "/activity",
+        "/ai",
+        "/ai-dashboard",
+        "/predictions",
+        "/recommendations",
+        "/impact",
+        "/follow-ups",
+        "/properties",
+        "/tenants",
+        "/rent",
+        "/maintenance",
+        "/leases",
+        "/expenses",
+      ],
+    },
+    sitemap: `${base}/sitemap.xml`,
+    host: base,
+  }
+}