refactor(front-stack): introduce sys-stk-front-base and semi-stateless stack; improve coturn role docs

- Extract common HTTPS + Cloudflare + handler bootstrap into new role sys-stk-front-base
- Update sys-stk-front-proxy, web-svc-cdn, web-svc-file, web-svc-html to depend on sys-stk-front-base
- Add new sys-stk-semi-stateless role combining front-base + back-stateless
- Update web-svc-coturn to use sys-stk-semi-stateless and rewrite README/meta with detailed Coturn description
- Unify sys-util-csp-cert README heading

Ref: ChatGPT conversation https://chatgpt.com/share/68d6cea2-3570-800f-acb3-c3277317f17b

roles/web-svc-coturn/meta/main.yml

@@ -1,7 +1,7 @@
 ---
 galaxy_info:
   author: "Kevin Veen-Birkenbach"
-  description: "Deploys a Coturn TURN/STUN server via Docker Compose, with automatic domain and port configuration for Nextcloud Talk."
+  description: "Deploys Coturn, a free and open-source TURN/STUN server"
   license: "Infinito.Nexus NonCommercial License"
   license_url: "https://s.infinito.nexus/license"
   company: |
@@ -12,12 +12,13 @@ galaxy_info:
     - coturn
     - turn
     - stun
+    - webrtc
     - docker
+    - stateless
+    - realtime
   repository: "https://s.infinito.nexus/code"
   issue_tracker_url: "https://s.infinito.nexus/issues"
-  documentation: "https://s.infinito.nexus/code/tree/main/roles/web-svc-coturn"
-  min_ansible_version: "2.9"
-  platforms:
-    - name: Any
-      versions:
-        - all
+  documentation: "https://github.com/coturn/coturn/wiki"
+  logo:
+    class: "webrtc"
+  run_after: []