feat: add knowledge markdown formatting and detail retrieval

- Implemented KnowledgeWebsiteMarkdownPrompt for formatting webpage content into Markdown.
- Added GetItemDetail method in KnowledgeHandler to retrieve knowledge item details.
- Introduced KnowledgeDetailDrawer component for displaying knowledge item details in the admin web interface.
- Created MarkdownPreview component for rendering Markdown content.
- Added knowledge chunking and URL parsing logic to handle webpage content extraction and formatting.
- Updated database schema to include markdown_content in knowledge_items table.

server/internal/tenant/transport/router.go

@@ -90,6 +90,7 @@ func RegisterRoutes(app *bootstrap.App) {
 	knowledge.PUT("/groups/:gid", knowledgeHandler.UpdateGroup)
 	knowledge.DELETE("/groups/:gid", knowledgeHandler.DeleteGroup)
 	knowledge.GET("/items", knowledgeHandler.ListItems)
+	knowledge.GET("/items/:id", knowledgeHandler.GetItemDetail)
 	knowledge.POST("/items/text", knowledgeHandler.CreateTextItem)
 	knowledge.POST("/items/url", knowledgeHandler.CreateURLItem)
 	knowledge.POST("/items/file", knowledgeHandler.CreateFileItem)