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/docker-compose.yml

@@ -8,6 +8,7 @@ services:
     environment:
       - VITE_SUPABASE_URL=${VITE_SUPABASE_URL}
       - VITE_SUPABASE_ANON_KEY=${VITE_SUPABASE_ANON_KEY}
+      - VITE_API_URL=${VITE_API_URL:-http://127.0.0.1:3003}
       - VITE_OPENAI_API_KEY=${VITE_OPENAI_API_KEY}
       - VITE_OPENROUTER_API_KEY=${VITE_OPENROUTER_API_KEY}
       - VITE_AI_MODEL=${VITE_AI_MODEL}