feat(08-02): implement crawl_comments method with hot sorting

- Add COMMENT_API_TEMPLATE for comment API URL
- Implement crawl_comments() returning CommentsResult
- Use order=hot for popular comments sorting
- Only fetch first-level comments (no nested replies)
- Add include_comments parameter to crawl_answer()
- Export CommentAuthor, CommentData, CommentsResult in __init__.py

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

kb_workflow/crawler/__init__.py

@@ -8,8 +8,17 @@ from .models import (
     ContentMetadata,
     AnswerData,
     ArticleData,
+    CommentAuthor,
+    CommentData,
+    CommentsResult,
     CrawlResult,
 )
+from .config import (
+    ProxyConfig,
+    CrawlerConfig,
+    get_crawler_config,
+    reset_crawler_config,
+)
 from .zhihu_crawler import ZhihuCrawler, ZhihuApiInterceptor
 
 __all__ = [
@@ -17,7 +26,14 @@ __all__ = [
     "ContentMetadata",
     "AnswerData",
     "ArticleData",
+    "CommentAuthor",
+    "CommentData",
+    "CommentsResult",
     "CrawlResult",
+    "ProxyConfig",
+    "CrawlerConfig",
+    "get_crawler_config",
+    "reset_crawler_config",
     "ZhihuCrawler",
     "ZhihuApiInterceptor",
 ]