feat(07-02): implement parse_json_cookies function

- Parse Chrome Cookie Editor JSON format
- Filter cookies by zhihu.com domain
- Handle malformed JSON with ValueError
- Handle file not found with ValueError
- Return cookie string in "name=value; name2=value2" format

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

kb_workflow/auth/cookie_manager.py

@@ -0,0 +1,51 @@
+"""Cookie 管理模块
+
+处理 Cookie 的导入、转换和持久化。
+"""
+
+import json
+from pathlib import Path
+from typing import List, Dict, Any
+
+
+def parse_json_cookies(json_path: str) -> str:
+    """从 JSON 文件解析 Cookie 为字符串格式
+
+    支持 Chrome Cookie Editor 导出的 JSON 格式:
+    [{"name": "z_c0", "value": "xxx", "domain": ".zhihu.com"}, ...]
+
+    Args:
+        json_path: JSON 文件路径
+
+    Returns:
+        Cookie 字符串，格式: "name1=value1; name2=value2"
+
+    Raises:
+        ValueError: JSON 格式无效或文件不存在
+    """
+    path = Path(json_path)
+    if not path.exists():
+        raise ValueError(f"Cookie file not found: {json_path}")
+
+    try:
+        with open(path, 'r', encoding='utf-8') as f:
+            cookies = json.load(f)
+    except json.JSONDecodeError as e:
+        raise ValueError(f"Invalid JSON format: {e}")
+
+    if not isinstance(cookies, list):
+        raise ValueError("Expected JSON array")
+
+    # 过滤知乎域名，转换为 name=value 格式
+    zhihu_cookies = []
+    for c in cookies:
+        if not isinstance(c, dict):
+            continue
+        domain = c.get('domain', '')
+        if 'zhihu.com' in domain:
+            name = c.get('name', '')
+            value = c.get('value', '')
+            if name and value:
+                zhihu_cookies.append(f"{name}={value}")
+
+    return '; '.join(zhihu_cookies)