feat: 添加 watch 和 check-update 命令 + OpenClaw 每日监控

- agent-reach check-update: 检查 GitHub 最新版本，展示更新内容
- agent-reach watch: 快速健康检查+版本检查，为定时任务设计
  - 全部正常只输出一行
  - 有问题才展开详情
- install.md 新增 Step 5: OpenClaw 用户可设置每日自动监控
  - Agent 主动问用户要不要设定时任务
  - 有问题才通知，没问题不打扰

docs/install.md

@@ -62,6 +62,23 @@ agent-reach configure proxy http://user:pass@ip:port
 
 Run `agent-reach doctor` one final time and report the results to your user.
 
+### Step 5: Set up daily monitoring (OpenClaw only)
+
+If you are running inside **OpenClaw**, ask your user:
+
+> "Agent Reach 安装好了。要不要我设一个每天自动检查的任务？它会帮你盯着这些渠道是否正常、有没有新版本。有问题才会通知你，没问题不打扰。"
+
+If the user agrees, create a **cron job** (daily, `sessionTarget: "isolated"`, `delivery: "announce"`) with this task:
+
+```
+运行 agent-reach watch 命令。
+如果输出包含"全部正常"，不需要通知用户，静默结束。
+如果输出包含问题（❌ ⚠️）或新版本（🆕），把完整报告发给用户，并建议修复方案。
+如果有新版本可用，问用户是否要升级（升级命令：pip install --upgrade https://github.com/Panniantong/agent-reach/archive/main.zip）。
+```
+
+If the user wants a different agent to handle it, let them choose.
+
 ---
 
 ## Quick Reference
@@ -70,6 +87,8 @@ Run `agent-reach doctor` one final time and report the results to your user.
 |---------|-------------|
 | `agent-reach install --env=auto` | Full auto-setup (installs deps + configures) |
 | `agent-reach doctor` | Show channel status |
+| `agent-reach watch` | Quick health + update check (for scheduled tasks) |
+| `agent-reach check-update` | Check for new versions |
 | `agent-reach configure twitter-cookies "..."` | Unlock Twitter search + posting |
 | `agent-reach configure proxy URL` | Unlock Reddit + Bilibili on servers |
 | `agent-reach read <url>` | Read any URL |