Fix/onboard oauth ux (#38)

* "fix(onboard): guide ccproxy install and auth in OAuth flow

  - Always show API Key / OAuth choice; prompt to install evoscientist[oauth]
    when ccproxy missing (mirrors iMessage imsg install UX)
  - Add _ccproxy_exe() helper: checks PATH then env bin dir (fixes conda envs
    where shutil.which may not find newly installed binaries)
  - Fix check_ccproxy_auth() false positive: ccproxy auth status exits 0 even
    when not authenticated; detect via output content + filter structlog noise
  - Silent install/login subprocesses; show browser URL as fallback
  - Reset anthropic/openai auth_mode to api_key when switching to non-Anthropic/
    OpenAI provider, preventing stale oauth config from triggering ccproxy error

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

* fix(onboard): update OAuth support details in README and zh-CN translation

README.zh-CN.md

@@ -217,6 +217,7 @@ EvoSci onboard
 
 > [!TIP]
 > 向导将引导你完成供应商选择、密钥验证、模型选择和工作区模式设置。
+> 支持 [Claude Code](https://claude.com/product/claude-code) 和 [Codex CLI](https://developers.openai.com/codex/cli/) 用户通过 OAuth 直连——无需 API Key。
 
 ![onboard](.github/assets/EvoScientist_onboard.png)
 
@@ -422,7 +423,7 @@ channel_enabled: "telegram,slack,feishu,qq"
 - [x] 👋 Human-in-the-loop 操作审批
 - [x] 🦾 智能体主动向人类澄清确认
 - [x] 📑 技术报告已发布
-- [ ] 🔐 OAuth 登录（Anthropic、OpenAI 等）
+- [x] 🔐 OAuth 登录（Anthropic、OpenAI 等）
 - [ ] 📺 带工作区的 Web 应用界面
 - [ ] 📹 Demo 与教程正在制作中
 - [ ] 📊 基准测试套件即将推出