fix(agent): authenticate agent control plane (#40737)

docker/.env.example

@@ -254,7 +254,7 @@ MARKETPLACE_URL=
 
 # Dify Agent backend
 AGENT_BACKEND_BASE_URL=http://agent_backend:5050
-# Bearer token for the Agent backend /runs API.
+# Bearer token for the Agent backend control-plane API.
 # Replace this development default in production.
 # Generate one with: python -c 'import secrets; print(secrets.token_urlsafe(32))'
 DIFY_AGENT_API_TOKEN=dify-agent-run-token-for-dev-only