Remove act_runner config file/mount — unreliable under Portainer git-stack deploy, and unnecessary

The bind-mounted relative path resolved to nothing once Portainer's cloned
checkout no longer persisted for the container's runtime, so Docker silently
created an empty directory there and act_runner crash-looped. act_runner
already auto-detects its own docker.sock without any custom config.

docker-compose.yml

@@ -73,11 +73,14 @@ services:
       # catthehacker/ubuntu:act-latest is the standard job-container image for
       # act/act_runner — includes git + docker CLI, which job steps need.
       GITEA_RUNNER_LABELS: docker:docker://catthehacker/ubuntu:act-latest
-      CONFIG_FILE: /etc/act_runner/config.yaml
+      # No custom config.yaml: act_runner already auto-detects its own bind-mounted
+      # docker.sock and passes it through to job containers with no extra config needed.
+      # (A relative-path bind-mounted config file here would also be unreliable under
+      # Portainer's git-stack deploy — its cloned checkout doesn't persist for the
+      # container's runtime, so the mount source can silently resolve to nothing.)
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
       - act_runner_data:/data
-      - ./act-runner-config.yaml:/etc/act_runner/config.yaml:ro
     networks:
       - web