Refactor workflow routing and greeting management in Brain classes

- Update WorkflowBrain to handle greeting playback more effectively, ensuring that the initial greeting completes before transitioning to the first node.
- Introduce new methods for managing greeting states and conditions, enhancing the interaction flow for user turns.
- Refactor WorkflowLLMRouter to improve routing logic and ensure proper handling of conditional paths.
- Enhance tests to verify the correct behavior of greeting management and routing under various scenarios, including waiting for audio playback to finish.
- Update frontend components to reflect changes in edge handling and improve user experience in workflow configurations.

frontend/src/components/workflow/ConditionEdge.tsx

@@ -49,7 +49,11 @@ export function ConditionEdge({
   const label = (
     (data?.label as string) ||
     (mode === "llm" ? (data?.condition as string) : "") ||
-    (mode === "expression" ? "变量表达式" : "默认路径")
+    (mode === "llm"
+      ? "大模型判断"
+      : mode === "expression"
+        ? "表达式"
+        : "默认路径")
   ).toString().trim();
   const expanded = hovered || selected;