feat(logout): wire injector to web-svc-logout and add robust CORS/CSP for /logout

- sys-front-inj-logout: depend on web-svc-logout (run-once guarded) and simplify task flow.
- web-svc-logout: align feature flags/formatting and extend CSP:
  - add cdn.jsdelivr.net to connect/script/style and quote values.
- Nginx: move CORS config into logout-proxy.conf.j2 with dynamic vars:
  - Access-Control-Allow-Origin set to canonical logout origin,
  - Allow-Credentials=true,
  - Allow-Methods=GET, OPTIONS,
  - basic headers list (Accept, Authorization),
  - cache disabled for /logout responses.
- Drop obsolete CORS var passing from 01_core.yml; headers now templated at proxy layer.

Prepares clean cross-origin logout orchestration from https://logout.veen.world.

Refs: ChatGPT discussion – https://chatgpt.com/share/68ebb75f-0170-800f-93c5-e5cb438b8ed4

roles/web-svc-logout/templates/logout-proxy.conf.j2

@@ -8,7 +8,11 @@ location = /logout {
     proxy_http_version 1.1;
 
     {# CORS headers – allow your central page to call this #}
-    {% include 'roles/sys-svc-proxy/templates/headers/access_control_allow.conf.j2' %}
+    {%- set aca_origin = "'{{ domains | get_url('web-svc-logout', WEB_PROTOCOL) }}' always" -%}
+    {%- set aca_credentials = "'true' always" -%}
+    {%- set aca_methods = "'GET, OPTIONS' always" -%}
+    {%- set aca_headers = "'Accept, Authorization' always" -%}
+    {%- include 'roles/sys-svc-proxy/templates/headers/access_control_allow.conf.j2' -%}
 
     {# Disable caching absolutely #}
     add_header Cache-Control "no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0" always;