chore: add env_file: stack.env to all compose services

Portainer git-stack deployments require an explicit env_file reference
in the compose file to load variables from the repo's stack.env.
Adds env_file: [stack.env] before every service-level environment:
block across all 10 stacks.

stacks/proxy/docker-compose.yml

@@ -22,6 +22,8 @@ services:
     ports:
       - "80:80"
       - "443:443"
+    env_file:
+      - stack.env
     environment:
       - CF_API_TOKEN=${CF_API_TOKEN}
     volumes: