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/configs/config.local.yaml.example

@@ -36,6 +36,7 @@ llm:
   provider: ark
   base_url: https://ark.cn-beijing.volces.com/api/v3
   model: doubao-seed-2-0-lite-260215
+  knowledge_url_model: doubao-seed-2-0-mini-260215
   timeout: 2m
   max_output_tokens: 4000
   temperature: 0.7