added Gitea runner image

gitea-runner/Dockerfile

@@ -0,0 +1,7 @@
+FROM alpine:3.24
+RUN echo "@testing https://dl-cdn.alpinelinux.org/alpine/edge/testing" >> /etc/apk/repositories
+RUN --mount=type=cache,target=/var/cache/apk apk update
+RUN --mount=type=cache,target=/var/cache/apk apk add gitea-runner@testing nodejs docker
+USER gitea-runner
+WORKDIR /var/lib/gitea-runner
+CMD ["/usr/bin/gitea-runner", "daemon", "--config", "/etc/gitea-runner/config.yaml"]