docs: update 3 docs with critical findings from author's research

AGENT.md:
- Expanded dimension 4 (niche analysis): ITF tennis/tier-3 esports = real edge,
  5min BTC/scalping = never follow, long holds (>7d) kill compounding
- Added edge disappearance warning (ArbTraderRookie wiped mid-analysis)
- Added 5 new AI agent rules: don't use copy_pnl alone, niche awareness,
  edge fragility, win rate is survivorship-biased, small capital = concentrate

日常使用.md:
- Added emergency exit procedure (host/flatten_positions.py)
- Added edge disappearance detection and response procedure

问题排查与踩坑记录.md:
- Added gotcha 7.11: win rate is survivorship-biased (90.6% shown = 48.3% real)
- Added gotcha 7.12: edge can vanish (wallet wiped from API mid-analysis)
- Added gotcha 7.13: long holds kill compounding (leegunner + lifetime
  but - to copy due to 7.6-day holds)
- Added gotcha 7.14: emergency exit tool (flatten_positions.py)

日常使用.md

@@ -354,6 +354,35 @@ journalctl -u copybot-paper --since "30 minutes ago" --no-pager | tail -30
 systemctl restart copybot-paper
 ```
 
+### 紧急退出（一键清仓所有 live 仓位）
+
+**什么时候用**：发现严重问题需要立刻清仓（bot 失控 / edge 消失 / 需要紧急撤资）
+
+```bash
+# 停 bot 防止它继续下单
+systemctl stop copybot-live
+
+# 一键市价卖出所有仓位
+cd /opt/winning-wallet-finder
+export LIVE_PRIVATE_KEY=$(grep LIVE_PRIVATE_KEY /etc/copybot/live.env | cut -d= -f2-)
+export HTTPS_PROXY=http://127.0.0.1:7890
+python3 host/flatten_positions.py
+```
+
+> ⚠️ 这是**真钱操作**，市价卖出可能有滑点损失。只在紧急情况用。
+
+### edge 消失（钱包突然不交易或从 API 消失）
+
+**怎么发现**：某个跟单钱包连续 1 周没有 FOLLOW 信号，或 watch_sharps 里突然找不到
+
+**原因**：作者研究发现 edge 可能随时消失（钱包可能被 Polymarket 封禁、改变策略、或信息源断了）
+
+**处理**：
+1. 确认钱包是否还在 watch_sharps.json 里
+2. 如果不在了 -> 从跟单配置里踢掉，从 bench 里选替补
+3. 如果还在但不交易 -> 观察 1 周，无改善则踢掉
+4. **赚钱了定期取出来**，不要假设 edge 永久存在
+
 ---
 
 ## 更新代码