Add act_runner compose snippet

compose-snippets/act_runner.yml

@@ -0,0 +1,25 @@
+# act_runner — Gitea Actions self-hosted runner
+# Deploy on Pi 5 (arrsstack). Registers at instance level — services all repos.
+#
+# Setup:
+#   1. Gitea → Site Administration → Actions → Runners → Create Runner → copy token
+#   2. echo "RUNNER_TOKEN=<token>" > .env
+#   3. docker compose up -d
+
+services:
+  act-runner:
+    image: gitea/act_runner:latest
+    container_name: act-runner
+    restart: unless-stopped
+    environment:
+      - GITEA_INSTANCE_URL=https://git.thewichersfamily.com
+      - GITEA_RUNNER_REGISTRATION_TOKEN=${RUNNER_TOKEN}
+      - GITEA_RUNNER_NAME=homelab-pi5
+      # Maps runs-on: labels to Docker images used for job containers
+      - GITEA_RUNNER_LABELS=ubuntu-latest:docker://node:20-bookworm,ubuntu-22.04:docker://node:20-bookworm
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock
+      - act_runner_data:/data
+
+volumes:
+  act_runner_data: