web-svc-collabora: localize vars, adjust CSP, fix systemd perms; refactor role composition

- sys-service:
  - Set explicit ownership and permissions for generated unit files:
    owner=root, group=root, mode=0644. Prevents drift and makes idempotence
    predictable when handlers reload/refresh systemd.

- web-svc-collabora:
  - Move cmp-docker-proxy include into tasks/01_core.yml and run it
    before Nginx config generation. Use public: true only to initialize the
    proxy/compose context and docker_compose_flush_handlers: true to ensure
    timely handler execution.
  - Define role-local variables domain and http_port in vars/main.yml
    and use {{ domain }} for the Nginx server file path. These values MUST
    be defined locally because they cannot be reliably imported via
    public: true — other roles may override them later in the play, leading
    to leakage and nondeterministic behavior. Localizing avoids precedence
    conflicts without resorting to host-wide set_fact.
  - CSP adjusted: add server.security.flags.style-src.unsafe-inline: true
    to accommodate Collabora’s inline styles (requested as “csr” in notes).
  - Minor variable alignment/cleanup and TODO note for future refactor.

- Housekeeping:
  - Rename task title to reflect {{ domain }} usage.

Refs:
- Discussion and rationale in this chat https://chatgpt.com/share/68a731aa-d394-800f-9eb4-2499f45ed54b (2025-08-21, Europe/Berlin).

roles/sys-service/tasks/05_service.yml

@@ -32,6 +32,9 @@
   template:
     src:  "{{ system_service_template_src }}"
     dest: "{{ [ PATH_SYSTEM_SERVICE_DIR, system_service_id | get_service_name(SOFTWARE_NAME) ] | path_join }}"
+    owner: root
+    group: root
+    mode: '0644'
   notify: "{{ 'reload system daemon' if system_service_uses_at else 'refresh systemctl service' }}"
 
 - name: refresh systemctl service when SYS_SERVICE_ALL_ENABLE