fix: rename act-runner to act_runner — podman-compose chokes on hyphens in service names

https://claude.ai/code/session_01FKCW3FDjNFj6jve4niMFXH

infra/docker-compose.yml

@@ -105,7 +105,7 @@ services:
   # ── Forgejo Actions runner ─────────────────────────────────────────────────
   # Obtain FORGEJO_RUNNER_TOKEN from Forgejo:
   #   Site Administration → Actions → Runners → Create new runner
-  act-runner:
+  act_runner:
     image: code.forgejo.org/forgejo/act_runner:latest
     restart: unless-stopped
     environment:
@@ -115,7 +115,7 @@ services:
       # Give the runner access to Podman so CI jobs can build/run containers.
       DOCKER_HOST: tcp://podman-proxy:2375
     volumes:
-      - act-runner-data:/data
+      - act_runner_data:/data
     depends_on:
       - forgejo
       - podman-proxy
@@ -192,7 +192,7 @@ networks:
 volumes:
   hiy-data:
   forgejo-data:
-  act-runner-data:
+  act_runner_data:
   caddy-data:
   caddy-config:
   hiy-pg-data: