feat(ai): 业务上下文感知与 A2UI 链路统一

- 新增代码内业务上下文元数据层（实体字典 + 三大闭环工作流）
- 新增 get_business_context / get_entity_schema / get_pending_tasks 运行时工具
- SYSTEM_PROMPT 与技能目录改为先查业务流程/待办再执行
- A2UI 增加 ai_a2ui_submissions 幂等表、表单过期、ui.artifact 事件
- 提交回灌携带 submissionId / fieldErrors / 下一步建议
- 前端 uiArtifacts 归一化与过期表单禁用

apps/admin/src/components/AiChat/useAiChatMessageActions.tsx

@@ -9,7 +9,7 @@ import { useSettingsStore } from '../../store/settings/settingsStore';
 import { aiChatApi, resolveImportPreflight, type ResolveImportPreflightInput } from './api';
 import { AiMessageContent } from './AiMessageContent';
 import { mapHistoryMessage } from './message-mappers';
-import { GongxueAiChatProvider } from './provider';
+import { GongxueAiChatProvider, mergeArtifactIntoMessage } from './provider';
 import {
   emptyAssistant,
   MessageHoverActions,
@@ -111,6 +111,11 @@ export function useAiChatMessageActions({
         },
       }));
     };
+    provider.onExternalArtifact = (messageId, artifact) => {
+      setMessage(messageId, (info) => ({
+        message: mergeArtifactIntoMessage(info.message, artifact),
+      }));
+    };
   }, [provider, setMessage]);
 
   requestingRef.current = isRequesting;