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/assets/less/bootstrap/wells.less

@@ -0,0 +1,29 @@
+//
+// Wells
+// --------------------------------------------------
+
+
+// Base class
+.well {
+  min-height: 20px;
+  padding: 19px;
+  margin-bottom: 20px;
+  background-color: @well-bg;
+  border: 1px solid @well-border;
+  border-radius: @border-radius-base;
+  .box-shadow(inset 0 1px 1px rgba(0,0,0,.05));
+  blockquote {
+    border-color: #ddd;
+    border-color: rgba(0,0,0,.15);
+  }
+}
+
+// Sizes
+.well-lg {
+  padding: 24px;
+  border-radius: @border-radius-large;
+}
+.well-sm {
+  padding: 9px;
+  border-radius: @border-radius-small;
+}