Fix: Optimize search functionality #3221 (#10002)

### What problem does this PR solve?

Fix: Optimize search functionality
- Fixed search limitations when no dataset is selected

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

web/src/locales/en.ts

@@ -1573,6 +1573,7 @@ This delimiter is used to split the input text into several text pieces echo of
       descriptionValue: 'You are an intelligent assistant.',
       okText: 'Save',
       cancelText: 'Cancel',
+      chooseDataset: 'Please select a dataset first',
     },
     language: {
       english: 'English',

web/src/locales/zh.ts

@@ -1485,6 +1485,7 @@ General：实体和关系提取提示来自 GitHub - microsoft/graphrag：基于
       descriptionValue: '你是一位智能助手。',
       okText: '保存',
       cancelText: '返回',
+      chooseDataset: '请先选择知识库',
     },
     language: {
       english: '英语',