feat(backend): add standalone data plane

Replace the Supabase application data plane with the Node/PostgreSQL API, migrate mobile, admin, web, and MCP callers, add controlled cutover tooling, and define hardened Dokploy infrastructure.

apps/admin/src/vite-env.d.ts

@@ -3,6 +3,7 @@
 interface ImportMetaEnv {
     readonly VITE_SUPABASE_URL: string;
     readonly VITE_SUPABASE_ANON_KEY: string;
+    readonly VITE_API_URL: string;
     readonly VITE_OPENAI_API_KEY: string;
 }