refactor: 移除 gate_bot，统一为三所架构并更新文档

删除 crypto_monitor_gate_bot 目录，中控与子代理改为 binance/okx/gate 三账户；
文档与 UI 文案「四所」改为「三所」；新增清库前一次性配置备份脚本。

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/patch_instance_theme_templates.py

@@ -5,7 +5,7 @@ from __future__ import annotations
 from pathlib import Path
 
 ROOT = Path(__file__).resolve().parents[1]
-EXCHANGES = ("crypto_monitor_binance", "crypto_monitor_okx", "crypto_monitor_gate", "crypto_monitor_gate_bot")
+EXCHANGES = ("crypto_monitor_binance", "crypto_monitor_okx", "crypto_monitor_gate")
 FILES = ("index.html", "login.html", "key_focus_v2.html", "order_focus_v2.html")
 
 SCRIPT_TAG = '    <script src="/static/instance_theme.js?v=4"></script>\n'