Enhance workflow engine and frontend components with transition speech support

- Introduce edge transition speech functionality in the WorkflowEngine to provide optional speech during node transitions.
- Update pipeline execution to utilize the new transition speech feature, enhancing user experience by masking delays during transitions.
- Modify frontend components to support transition speech in edge specifications, allowing users to define and edit transition speech for edges.
- Refactor edge handling logic in the WorkflowEditor to accommodate the new transition speech field, improving workflow management capabilities.

frontend/src/components/workflow/WorkflowEditor.tsx

@@ -120,7 +120,12 @@ function fromFlow(nodes: Node[], edges: Edge[]): WorkflowGraph {
       id: e.id,
       source: e.source,
       target: e.target,
-      data: (e.data as { condition?: string; label?: string }) ?? {},
+      data:
+        (e.data as {
+          condition?: string;
+          label?: string;
+          transition_speech?: string;
+        }) ?? {},
     })),
   };
 }
@@ -238,7 +243,14 @@ function Canvas({
   );
 
   const updateEdgeData = useCallback(
-    (id: string, patch: { condition?: string; label?: string }) => {
+    (
+      id: string,
+      patch: {
+        condition?: string;
+        label?: string;
+        transition_speech?: string;
+      },
+    ) => {
       setEdges((es) =>
         es.map((e) =>
           e.id === id ? { ...e, data: { ...(e.data ?? {}), ...patch } } : e,
@@ -677,12 +689,23 @@ function EdgeForm({
   onDelete,
 }: {
   edge: Edge;
-  onSave: (patch: { condition: string; label: string }) => void;
+  onSave: (patch: {
+    condition: string;
+    label: string;
+    transition_speech: string;
+  }) => void;
   onDelete: () => void;
 }) {
-  const data = (edge.data ?? {}) as { condition?: string; label?: string };
+  const data = (edge.data ?? {}) as {
+    condition?: string;
+    label?: string;
+    transition_speech?: string;
+  };
   const [label, setLabel] = useState(data.label ?? "");
   const [condition, setCondition] = useState(data.condition ?? "");
+  const [transitionSpeech, setTransitionSpeech] = useState(
+    data.transition_speech ?? "",
+  );
 
   return (
     <>
@@ -718,6 +741,22 @@ function EdgeForm({
             className="resize-none border-hairline-strong bg-background text-foreground placeholder:text-muted-soft"
           />
         </div>
+
+        <div className="flex flex-col gap-2">
+          <label className="text-sm font-medium text-foreground">
+            过渡语(可选)
+          </label>
+          <Textarea
+            rows={2}
+            value={transitionSpeech}
+            placeholder="切换到下一节点前先说的一句过渡语,用于掩盖延迟,例如:好的,我帮你转接。"
+            onChange={(e) => setTransitionSpeech(e.target.value)}
+            className="resize-none border-hairline-strong bg-background text-foreground placeholder:text-muted-soft"
+          />
+          <span className="text-xs text-muted-soft">
+            命中该条件、切换节点的瞬间播报,不写入对话上下文。
+          </span>
+        </div>
       </div>
 
       <DialogFooter className="flex-row justify-between sm:justify-between">
@@ -729,7 +768,13 @@ function EdgeForm({
           <Trash2 size={15} />
           删除连线
         </Button>
-        <Button onClick={() => onSave({ condition, label })}>保存条件</Button>
+        <Button
+          onClick={() =>
+            onSave({ condition, label, transition_speech: transitionSpeech })
+          }
+        >
+          保存条件
+        </Button>
       </DialogFooter>
     </>
   );