fix(cli): use json mode for model_dump serialization

Ensure Pydantic model serializes to JSON-compatible format.

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

.planning/REQUIREMENTS.md

@@ -1,46 +0,0 @@
-# Requirements: v1.4 Zhihu Anti-Crawler
-
-**Defined:** 2026-03-18
-**Core Value:** 绕过知乎反爬检测，让爬虫正常工作
-
-## v1 Requirements
-
-### 指纹伪装 (Stealth)
-
-- [x] **STEALTH-01**: 隐藏 navigator.webdriver 属性
-- [x] **STEALTH-02**: 移除 Playwright 特有的 JS 属性（__playwright, pwInspect 等）
-- [x] **STEALTH-03**: 模拟正常浏览器的 Chrome 属性
-- [x] **STEALTH-04**: 修改 User-Agent 为正常浏览器格式
-
-### 集成验证 (Verify)
-
-- [x] **VERIFY-01**: ZhihuCrawler 集成指纹伪装后能正常访问问答页面
-- [x] **VERIFY-02**: 保持现有功能不变（登录、Cookie、内容爬取）
-
-## Out of Scope
-
-| Feature | Reason |
-|---------|--------|
-| 其他平台适配 | 本里程碑只针对知乎 |
-| 验证码识别 | 知乎主要用二维码登录，验证码场景少 |
-| 代理池扩展 | v1.3 已实现，本版本不改动 |
-| 行为伪装（鼠标轨迹等） | 先用最小改动验证效果，如需要再加 |
-
-## Traceability
-
-| Requirement | Phase | Status |
-|-------------|-------|--------|
-| STEALTH-01 | Phase 11 | Complete (11-01) |
-| STEALTH-02 | Phase 11 | Complete (11-01) |
-| STEALTH-03 | Phase 11 | Complete (11-01) |
-| STEALTH-04 | Phase 11 | Complete (11-01) |
-| VERIFY-01 | Phase 11 | Complete (11-02) |
-| VERIFY-02 | Phase 11 | Complete (11-02) |
-
-**Coverage:**
-- v1 requirements: 6 total
-- Mapped to phases: 6
-- Unmapped: 0 ✓
-
----
-*Requirements defined: 2026-03-18*

kb_workflow/cli.py

@@ -165,7 +165,7 @@ def login_command(
         result = login.login_by_qrcode()
         if result.success and result.cookie_str:
             manager.save_cookie(result.cookie_str)
-        return result.model_dump()
+        return result.model_dump(mode='json')
 
     except Exception as e:
         return {"success": False, "error": str(e)}