feat: add fallback mode for AI agents and update knowledge base handling

- Introduced AIAgentFallbackMode with options for NoAnswer and SuggestRetry.
- Updated AI agent edit component to include fallback mode selection.
- Modified API types and payloads to accommodate fallback mode.
- Removed deprecated KnowledgeFallbackMode and related logic from knowledge base.
- Adjusted knowledge retrieval and response handling to utilize new fallback logic.
- Updated tests to reflect changes in fallback mode handling for AI agents.

dashboard/lib/generated/enums.ts

@@ -1,5 +1,14 @@
 // Code generated by cmd/enums/generator.go. DO NOT EDIT.
 
+export enum AIAgentFallbackMode {
+  NoAnswer = 1,
+  SuggestRetry = 2,
+}
+export const AIAgentFallbackModeLabels: Record<AIAgentFallbackMode, string> = {
+  [AIAgentFallbackMode.NoAnswer]: "直接声明无答案",
+  [AIAgentFallbackMode.SuggestRetry]: "建议补充信息",
+}
+
 export enum AIAgentHandoffMode {
   WaitPool = 1,
   DefaultTeamPool = 2,
@@ -274,17 +283,6 @@ export const KnowledgeDocumentIndexStatusLabels: Record<KnowledgeDocumentIndexSt
   [KnowledgeDocumentIndexStatus.Failed]: "索引失败",
 }
 
-export enum KnowledgeFallbackMode {
-  NoAnswer = 1,
-  SuggestRetry = 2,
-  TransferHuman = 3,
-}
-export const KnowledgeFallbackModeLabels: Record<KnowledgeFallbackMode, string> = {
-  [KnowledgeFallbackMode.NoAnswer]: "直接声明无答案",
-  [KnowledgeFallbackMode.SuggestRetry]: "建议重试",
-  [KnowledgeFallbackMode.TransferHuman]: "转人工",
-}
-
 export enum KnowledgeFeedbackType {
   Like = 1,
   Dislike = 2,