feat(web): enhance knowledge base sharing with stop share feedback

- Fix file download URL to use absolute API path instead of apiPrefix variable
- Add stopShareSuccess i18n message for English locale
- Add stopShareSuccess i18n message for Chinese locale
- Update ShareModal to display different success messages based on share toggle state
- Show "Sharing is off" message when disabling knowledge base sharing
- Improve user feedback when toggling share status on/off

web/src/i18n/en.ts

@@ -580,6 +580,7 @@ export const en = {
     knowledgeBase: {
       pleaseUploadFileFirst: 'Please upload file first',
       shareSuccess: 'Share successfully',
+      stopShareSuccess: 'Sharing is off. Access denied. ',
       shareFailed: 'Share failed',
       allModels: 'All Models',
       knowledgeBaseInfo: 'Knowledge base information',

web/src/i18n/zh.ts

@@ -122,6 +122,7 @@ export const zh = {
       preview: '预览',
       pleaseUploadFileFirst: '请先上传文件',
       shareSuccess: '分享成功',
+      stopShareSuccess: '已取消分享，对方将无法访问该知识库',
       shareFailed: '分享失败',
       allModels: '所有模型',
       knowledgeBaseInfo: '知识库信息',