Refactor TURN/STUN handling:

- Split internal/external Coturn for BBB and Nextcloud
- Added dedicated relay port ranges per app
- Updated env and compose overrides for coturn
- Ensure coturn role is loaded conditionally
- Standardize credential/env passing for coturn
@See https://chatgpt.com/share/68d6f376-4878-800f-b4f7-62822caa49ea

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

@@ -1,3 +1,4 @@
+username: coturnconsumer
 server:
   domains:
     canonical:
@@ -10,4 +11,4 @@ docker:
     redis:
       enabled:  false
     database: 
-      enabled:  false
+      enabled:  false