Refactor run-once logic across multiple roles and integrate unified utils/run_once.yml

This commit standardizes all run-once implementations across the following roles:
- desk-git
- dev-fakeroot
- dev-git
- dev-python-yaml
- sys-lock
- sys-svc-certs (wildcard flavor)
- update-apt
- update-pacman
- update-compose
- user-root (moved logic to 01_core.yml + unified run-once handling)
- web-app-matomo
- web-svc-libretranslate

All roles now:
- Use a block guarded by 'run_once_<role>' facts
- Trigger run-once state through utils/run_once.yml
- Optionally disable handler flushing via 'flush_handlers: false'
- Achieve consistent per-host one-time execution semantics

Conversation reference: https://chatgpt.com/share/692c7fbb-ff68-800f-8cb4-4b132cffc8e4

roles/dev-fakeroot/tasks/main.yml

@@ -1,11 +1,11 @@
 ---
-- name: Install fakeroot
-  community.general.pacman:
-    name: fakeroot
-    state: present
-  when: run_once_dev_fakeroot is not defined
+- when: run_once_dev_fakeroot is not defined
+  block:
+    - name: Install fakeroot
+      community.general.pacman:
+        name: fakeroot
+        state: present
 
-- name: run the fakeroot tasks once
-  set_fact:
-    run_once_dev_fakeroot: true
-  when: run_once_dev_fakeroot is not defined
+    - include_tasks: utils/run_once.yml
+      vars:
+        flush_handlers: false