Add postgres to infra network

Postgres serves both infra (gitea) and atproto services.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker-compose.yml

@@ -13,6 +13,7 @@ services:
       - pgdata:/var/lib/postgresql/data
       - ./init:/docker-entrypoint-initdb.d:ro
     networks:
+      - infra
       - atproto
     # Port exposed for local debugging (using 5433 to avoid conflict with local postgres)
     ports:
@@ -33,6 +34,8 @@ volumes:
   pgdata:
 
 networks:
+  infra:
+    external: true
   atproto:
     name: atproto
     driver: bridge