feat: 后端全量更新 - 含所有本次需求

- Contract.php: 返回合约账户余额(balance_contract)
- My.php: 地址管理增加BTC/ETH
- AppContract.php: 一键平仓(closeall)
- AppProxy.php: 代理专属注册链接 + 分级权限(L1/L2)
- site.php: 手续费减半(0.018→0.009)
- agent_permission_setup.sql: 代理权限SQL
- crypto_news_crawler.py: 新闻自动采集脚本

public/GoJS-master/learn/kod/static/others/app/sw.js

@@ -0,0 +1,9 @@
+const cacheName = 'kodcloud';
+const staticAssets = [];
+self.addEventListener('install', async e => {
+});
+self.addEventListener('activate', e => {
+    self.clients.claim();
+});
+self.addEventListener('fetch', async e => {
+});