CORS/CSP hardening & centralization

- Add reusable Nginx include: roles/sys-svc-proxy/templates/headers/access_control_allow.conf.j2
  (dynamic ACAO/credentials/methods/headers via role vars)
- Set global 'Vary: Origin' in nginx.conf.j2 to prevent cache poisoning
- CSP: allow Simple Icons via connect-src when feature is enabled
- Front proxy: rename vars to lowercase + flush handlers after config deploy
- Desktop: gate & load Simple Icons role; inject brand logos when enabled
- Bluesky + Logout: replace inline CORS with centralized include
- Simpleicons: public CORS (ACAO='*', no credentials), keep GET/OPTIONS, allow headers
- Taiga: adjust canonical domain to taiga.kanban.{{ PRIMARY_DOMAIN }}
- LibreTranslate: remove unused images/versions keys

Fixes: https://open.project.infinito.nexus/projects/cymais/work_packages/342/activity
Discussion: https://chatgpt.com/share/68da5e27-ffd4-800f-91a3-0ef103058d44

roles/sys-stk-front-proxy/tasks/01_base.yml

@@ -6,10 +6,10 @@
   include_role:
     name: sys-util-csp-cert
 
-- name: "Copy nginx config to '{{ FRONT_PROXY_DOMAIN_CONF_DST }}'"
+- name: "Copy nginx config to '{{ front_proxy_domain_conf_dst }}'"
   template:
-    src:  "{{ FRONT_PROXY_DOMAIN_CONF_SRC }}"
-    dest: "{{ FRONT_PROXY_DOMAIN_CONF_DST }}"
+    src:  "{{ front_proxy_domain_conf_src }}"
+    dest: "{{ front_proxy_domain_conf_dst }}"
   register: nginx_conf
   notify: restart openresty
 
@@ -28,4 +28,7 @@
     when:
     - site_check.status is defined
     - not site_check.status in [200,301,302]
-  when: not nginx_conf.changed
+  when: not nginx_conf.changed
+
+- name: "Restart Webserver for '{{ front_proxy_domain_conf_dst }}'"
+  meta: flush_handlers