feat(08-01): implement ZhihuCrawler with API interception

- Add ZhihuCrawler class with crawl_answer() and crawl_article() methods
- Implement ZhihuApiInterceptor for capturing /api/v4/ responses
- Add _parse_author(), _parse_metadata(), _parse_answer_data(), _parse_article_data() helpers
- Support DOM parsing fallback for zhuanlan articles
- Export ZhihuCrawler and ZhihuApiInterceptor from __init__.py

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

kb_workflow/crawler/__init__.py

@@ -10,6 +10,7 @@ from .models import (
     ArticleData,
     CrawlResult,
 )
+from .zhihu_crawler import ZhihuCrawler, ZhihuApiInterceptor
 
 __all__ = [
     "AuthorInfo",
@@ -17,4 +18,6 @@ __all__ = [
     "AnswerData",
     "ArticleData",
     "CrawlResult",
+    "ZhihuCrawler",
+    "ZhihuApiInterceptor",
 ]