Build gitea-runner with docker CLI installed natively

Mounting host docker binary failed due to glibc/musl incompatibility.
Instead, extend the act_runner image and install docker-cli and
docker-cli-compose via apk.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -178,7 +178,9 @@ services:
             - SYMFONY__ENV__DATABASE_PASSWORD=${POSTGRES_PASSWORD}
 
     gitea-runner:
-        image: gitea/act_runner:latest
+        build:
+            context: ./gitea-runner
+            dockerfile: Dockerfile
         container_name: "${GITEA_RUNNER_HOST}"
         environment:
             GITEA_RUNNER_NAME: ${GITEA_RUNNER_NAME}
@@ -190,8 +192,6 @@ services:
             - ./gitea-runner/config.yaml:/config.yaml
             - ./gitea-runner/data:/data
             - /var/run/docker.sock:/var/run/docker.sock # WARNING: Docker socket mount gives container host-level access. Runner is in 'disabled' profile to mitigate risk.
-            - /usr/bin/docker:/usr/bin/docker:ro
-            - /usr/lib/docker/cli-plugins:/usr/lib/docker/cli-plugins:ro
             - /home/adamf/deploy/web_server:/home/adamf/deploy/web_server # Same path on host and container so docker compose bind mounts resolve correctly
         restart: unless-stopped
         networks: