Add registry-ui, automated GC, and Gitea runner/rate-limit fixes

- Deploy joxit/docker-registry-ui at cr.ladkau.de/ (Traefik routes
  /v2/ to registry, everything else to UI; REGISTRY_SECURED=true)
- Add weekly cron job (Sunday 03:00) to delete stale uploads, run
  registry garbage-collect, and prune dangling host images
- Remove rate-limit@docker middleware from Gitea router (act_runner
  polling at 2s intervals exceeded the 60 req/min limit)
- Set Traefik websecure readTimeout: 0 to fix large layer upload 499s
- Remove registry rate-limit middleware (was blocking concurrent pushes)

ansible/roles/registry/tasks/main.yml

@@ -38,3 +38,23 @@
     state: present
     pull: missing
   tags: registry
+
+- name: Deploy registry GC script
+  ansible.builtin.template:
+    src: registry-gc.sh.j2
+    dest: /usr/local/bin/registry-gc
+    owner: root
+    group: root
+    mode: "0750"
+  tags: registry
+
+- name: Schedule weekly registry GC cron job
+  ansible.builtin.cron:
+    name: registry-gc
+    user: root
+    weekday: "0"
+    hour: "3"
+    minute: "0"
+    job: /usr/local/bin/registry-gc >> /var/log/registry-gc.log 2>&1
+    state: present
+  tags: registry