docs(08): align all .example config files with SSOT architecture

config/frontend.yaml.example

@@ -6,11 +6,9 @@
 
 # --- API Connection ---
 api:
-  # Base URL of the backend API
-  # Default: http://localhost:8916
-  # Environment: FRONTEND_API_BACKEND_URL or BACKEND_URL
-  backend_url: "http://localhost:8916"
-
+  # Note: backend_url is dynamically injected by the launcher script
+  # based on network.yaml settings to ensure SSOT integrity.
+  
   # API timeout in milliseconds
   # Default: 30000 (30 seconds)
   # Environment: FRONTEND_API_TIMEOUT_MS