fix(crawler): resolve circular import in zhihu_crawler

Circular import chain:
  zhihu_crawler -> pipeline.config -> pipeline.platforms -> zhihu_crawler

Fix: Lazy import get_settings() inside _get_cookie() method instead of
module-level import.

kb_workflow/crawler/zhihu_crawler.py

@@ -19,7 +19,8 @@ from playwright.sync_api import Route, Response, sync_playwright
 from tenacity import Retrying, stop_after_attempt, wait_exponential, RetryError
 
 from kb_workflow.metadata.zhihu_extractor import PlaywrightBrowser
-from kb_workflow.pipeline.config import get_settings
+# NOTE: get_settings is imported lazily in _get_cookie() to avoid circular import
+# Circular: zhihu_crawler -> pipeline.config -> pipeline.platforms -> zhihu_crawler
 from .models import (
     AnswerData,
     ArticleData,
@@ -129,6 +130,9 @@ class ZhihuCrawler:
         Returns:
             Cookie string from settings
         """
+        # Lazy import to avoid circular dependency:
+        # zhihu_crawler -> pipeline.config -> pipeline.platforms -> zhihu_crawler
+        from kb_workflow.pipeline.config import get_settings
         settings = get_settings()
         return settings.zhihu_cookie.get_secret_value()