Add Clay agent interface, fix registry UI routing, and misc improvements

- Deploy Clay (claude Code web UI) at agent.ladkau.de behind basic auth;
  Traefik proxies to clay's HTTPS port 2633 with insecureSkipVerify
- Document MCP server persistence: binaries need to be baked into the
  Dockerfile, config in /opt/clay/data survives rebuilds
- Document scheduled agent workflows via Gitea Actions on.schedule with
  email reporting via Gmail SMTP
- Fix registry UI: split /v2/ (registry) and / (UI) into separate Traefik
  routers; add registry_internal network
- Add weekly registry GC cron job (/usr/local/bin/registry-gc)
- Remove rate-limit middleware from Gitea router (act_runner polling
  exceeded 60 req/min limit)
- Set Traefik websecure readTimeout: 0 to fix large layer upload 499s

ansible/roles/clay/handlers/main.yml

@@ -0,0 +1,16 @@
+---
+- name: Rebuild and restart clay
+  community.docker.docker_image:
+    name: clay:local
+    build:
+      path: "{{ clay_data_dir }}"
+    source: build
+    force_source: true
+    state: present
+  notify: Restart clay
+
+- name: Restart clay
+  community.docker.docker_compose_v2:
+    project_src: "{{ clay_data_dir }}"
+    state: present
+    recreate: always