fix(reddit): switch to Exa-only for search and read, remove proxy dependency

Reddit blocks nearly all non-browser access at IP level (including ISP proxies).
Switch Reddit channel to use Exa exclusively:
- Search: web_search_exa with includeDomains: ["reddit.com"]
- Read: crawling_exa for full post + comments
- check() now verifies Exa availability instead of probing Reddit API
- tier changed from 1 (needs config) to 0 (zero config)
- Removed reddit_proxy from config, CLI, and setup guide
- Updated all docs (README, README_en, install.md, SKILL.md, references)
- Fixed xreach→bird references in references/social.md

Fixes #218, Fixes #222, Fixes #221

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

README.md

@@ -73,7 +73,7 @@ AI Agent 已经能帮你写代码、改文档、管项目——但你让它去
 | 📦 **GitHub** | 读公开仓库 + 搜索 | 私有仓库、提 Issue/PR、Fork | 告诉 Agent「帮我登录 GitHub」 |
 | 🐦 **Twitter/X** | 读单条推文 | 搜索推文、浏览时间线、发推 | 告诉 Agent「帮我配 Twitter」 |
 | 📺 **B站** | 本地：字幕提取 + 搜索 | 服务器也能用 | 告诉 Agent「帮我配代理」 |
-| 📖 **Reddit** | 搜索（通过 Exa 免费） | 读帖子和评论 | 告诉 Agent「帮我配代理」 |
+| 📖 **Reddit** | 搜索 + 读帖子和评论（通过 Exa） | — | 无需配置（自动通过 Exa） |
 | 📕 **小红书** | — | 阅读、搜索、发帖、评论、点赞 | 告诉 Agent「帮我配小红书」 |
 | 🎵 **抖音** | — | 视频解析、无水印下载链接获取 | 告诉 Agent「帮我配抖音」 |
 | 💼 **LinkedIn** | Jina Reader 读公开页面 | Profile 详情、公司页面、职位搜索 | 告诉 Agent「帮我配 LinkedIn」 |
@@ -173,7 +173,7 @@ channels/
 ├── youtube.py      → yt-dlp          ← 可以换成 YouTube API、Whisper……
 ├── github.py       → gh CLI          ← 可以换成 REST API、PyGithub……
 ├── bilibili.py     → yt-dlp          ← 可以换成 bilibili-api……
-├── reddit.py       → JSON API + Exa  ← 可以换成 PRAW、Pushshift……
+├── reddit.py       → Exa             ← 搜索+阅读，无需代理
 ├── xiaohongshu.py  → mcporter MCP    ← 可以换成其他 XHS 工具……
 ├── douyin.py       → mcporter MCP    ← 可以换成其他抖音工具……
 ├── linkedin.py     → linkedin-mcp    ← 可以换成 LinkedIn API……
@@ -293,9 +293,9 @@ Agent Reach uses the bird CLI with cookie auth — zero API fees. After installi
 </details>
 
 <details>
-<summary><strong>Reddit 返回 403 / 服务器 IP 被封怎么办？</strong></summary>
+<summary><strong>Reddit 返回 403 怎么办？</strong></summary>
 
-Reddit 封锁数据中心 IP。配置一个住宅代理即可解决：`agent-reach configure proxy http://user:pass@ip:port`。推荐 Webshare ($1/月)。本地电脑一般不会遇到这个问题。
+Agent Reach 已改为通过 Exa 搜索和阅读 Reddit 内容，完全绕过 Reddit API 的 IP 封锁。无需代理，无需额外配置。运行 `agent-reach install --env=auto` 自动安装 Exa。
 </details>
 
 <details>
@@ -327,7 +327,7 @@ Yes! Agent Reach is an installer + configuration tool — any AI coding agent th
 <details>
 <summary><strong>Is this free? Any API costs?</strong></summary>
 
-100% free. All backends are open-source tools (bird CLI, yt-dlp, Jina Reader, Exa, etc.) that don't require paid API keys. The only optional cost is a residential proxy (~$1/month) if you need Reddit/Bilibili access from a server.
+100% free. All backends are open-source tools (bird CLI, yt-dlp, Jina Reader, Exa, etc.) that don't require paid API keys. The only optional cost is a residential proxy (~$1/month) if you need Bilibili access from a server. Reddit now works free via Exa without any proxy.
 </details>
 
 ---