feat(runner): add Gitea act_runner docker setup

Compose service registers against git.wampler.us via act_runner,
mounts docker.sock for job execution. Secrets and runtime state
(.env, data/) kept out of git.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

runner/compose.yml

@@ -0,0 +1,20 @@
+services:
+  runner:
+    image: gitea/act_runner:latest
+    container_name: gitea-runner
+    restart: unless-stopped
+    environment:
+      - CONFIG_FILE=/config.yaml
+      - GITEA_INSTANCE_URL=${INSTANCE_URL}
+      - GITEA_RUNNER_REGISTRATION_TOKEN=${REGISTRATION_TOKEN}
+      - GITEA_RUNNER_NAME=${RUNNER_NAME}
+      - GITEA_RUNNER_LABELS=${RUNNER_LABELS}
+    volumes:
+      - ./config.yaml:/config.yaml
+      - ./data:/data
+      - /var/run/docker.sock:/var/run/docker.sock
+    deploy:
+      resources:
+        limits:
+          memory: 2G
+          cpus: '2.0'