feat: migrate all stacks to Coolify (proxy network, clean labels, pull_policy)

- Remove traefik.enable, traefik.docker.network, traefik.http.routers.* from all services
- Keep traefik.http.services.<name>.loadbalancer.server.port labels
- Keep all middleware definitions (forwardauth, headers, redirects)
- Add pull_policy: always to main/frontend services
- Add proxy network + label to gitea and karakeep (previously missing)
- Add COOLIFY-TEMPLATE.md reference guide

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

mail-relay/docker-compose.yml

@@ -2,6 +2,7 @@ services:
   mail-relay:
     image: ${MAIL_RELAY_IMAGE}
     container_name: mail-relay
+    pull_policy: always
     restart: unless-stopped
     environment:
       TZ: ${TZ}
@@ -49,4 +50,4 @@ networks:
     driver: bridge
     ipam:
       config:
-        - subnet: ${MAIL_RELAY_SUBNET}
+        - subnet: ${MAIL_RELAY_SUBNET}