fix(svc-ai-searxng): register the compose handlers before notifying them

The role renders its settings.yml, which notifies compose-up, without ever loading the sys-svc-compose handlers. A local deploy hides that because a neighbouring role in the same play registers them first; a CI row deploys the role alone and the play dies with "The requested handler 'compose-up' was not found". The loader moves in front of the first template, the way svc-db-qdrant already does it and the way 95186163aa fixed the same class for sys-stk-backend.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

roles/svc-ai-searxng/tasks/00_core.yml

@@ -1,6 +1,10 @@
 ---
 - include_tasks: utils/once/flag.yml
 
+- include_tasks: utils/load/handlers.yml
+  vars:
+    handler_role_name: "sys-svc-compose"
+
 - name: "📄 Render the search engine settings (local + swarm peers)"
   ansible.builtin.include_tasks:
     file: "{{ lookup('path_absolute', 'roles/sys-svc-compose/tasks/utils/render_replicated_templates.yml') }}"