fix: install Docker CLI in forgejo-runner container

The forgejo-runner image doesn't include Docker CLI by default, causing
the startup script to hang waiting for Docker to be ready. Install
docker-cli via apk during startup to enable Docker socket access.

This completes the DinD setup for the runner.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/forgejo-runner/forgejo-runner-statefulset.yaml

@@ -51,6 +51,9 @@ spec:
         - sh
         - -c
         - |
+          # Install Docker CLI
+          apk add --no-cache docker-cli
+
           # Wait for Forgejo to be ready
           while ! wget -q -O- https://forgejo.basicstack.de/api/healthz > /dev/null 2>&1; do
             echo "Waiting for Forgejo to be ready..."