feat: support multiple Gitea instances for actions runner

The gitea-actions role now uses a `gitea_runners` list instead of a
single `gitea_instance_url`. Each instance gets its own config, systemd
service, working directory, and cache. Migrates from the old single
`act_runner.service` to per-instance `act_runner-{name}.service`.

Adds git.skudak.com alongside git.debyl.io as runner targets.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ansible/roles/gitea-actions/handlers/main.yml

@@ -1,10 +1,11 @@
 ---
-- name: restart act_runner
+- name: restart act_runner services
   become: true
   ansible.builtin.systemd:
-    name: act_runner
+    name: "act_runner-{{ item.name }}"
     state: restarted
     daemon_reload: true
+  loop: "{{ gitea_runners }}"
 
 - name: restart podman socket
   become: true