fix: update callers to use NewLLMRouterDefault

Use NewLLMRouterDefault(kb) instead of NewLLMRouter(kb) in:
- action/router.go
- cmd/starter/main.go

The NewLLMRouter now requires LLMRouterConfig{} struct.
Backward compat wrapper NewLLMRouterDefault() maintains old API.

cmd/starter/main.go

@@ -218,7 +218,7 @@ func runRoutingWorkflow(c client.Client, routeMsg, specFile string, isCron, dryR
 			logging.Fatal("failed to load knowledge base", logging.Err(err))
 		}
 
-		router, err := routing.NewLLMRouter(kb)
+		router, err := routing.NewLLMRouterDefault(kb)
 		if err != nil {
 			logging.Fatal("failed to create LLM router", logging.Err(err))
 		}