Added env file support

README.md

@@ -96,6 +96,14 @@ Port the app listens on inside the container (default `3000`)
 
 Extra `KEY=VALUE` docker build args (space-separated)
 
+`env-vars`
+
+Runtime env vars for the container, one `KEY=VALUE` per line. Merged on top of `/opt/apps/${app-name}/.env.${environment}` on the runner — keys defined here win. Reference secrets here so values stay masked in logs.
+
+    env-vars: |
+      DATABASE_URL=${{ secrets.DATABASE_URL }}
+      API_KEY=${{ secrets.API_KEY }}
+
 ### Cleanup
 
 Stops the preview container and removes its Pangolin resource. Intended for `delete` branch events — the slug is derived from the branch name internally.