Add Telegram watcher, dashboard docs, and deployment config

- scripts/telegram-watcher.js: push ENTER signals from signals.csv to Telegram
- DASHBOARD_GUIDE.md: complete dashboard field-by-field documentation
- package.json: add watch:telegram npm script
- .env.example: deployment env template
- .gitignore: exclude ecosystem.config.cjs/start.sh (server-only with paths)

Watcher reads recommendation column and triggers on:
  - transition NO_TRADE -> ENTER:side
  - flip ENTER:UP <-> ENTER:DOWN
  - 30s cooldown prevents spam

.env.example

@@ -0,0 +1,11 @@
+# Telegram (revoke 后用新 token)
+TELEGRAM_BOT_TOKEN=
+TELEGRAM_CHAT_ID=
+TELEGRAM_COOLDOWN_MS=30000
+
+# Polygon RPC
+POLYGON_RPC_URL=https://lb.drpc.live/polygon/your-key
+POLYGON_WSS_URLS=wss://lb.drpc.live/polygon/your-key
+
+# Proxy (服务器本地通常不需要；国内云服务器必须)
+# HTTPS_PROXY=http://user:pass@ip:7890