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/libs/bootstrap/less/breadcrumbs.less

@@ -0,0 +1,26 @@
+//
+// Breadcrumbs
+// --------------------------------------------------
+
+
+.breadcrumb {
+  padding: @breadcrumb-padding-vertical @breadcrumb-padding-horizontal;
+  margin-bottom: @line-height-computed;
+  list-style: none;
+  background-color: @breadcrumb-bg;
+  border-radius: @border-radius-base;
+
+  > li {
+    display: inline-block;
+
+    + li:before {
+      padding: 0 5px;
+      color: @breadcrumb-color;
+      content: "@{breadcrumb-separator}\00a0"; // Unicode space added since inline-block means non-collapsing white-space
+    }
+  }
+
+  > .active {
+    color: @breadcrumb-active-color;
+  }
+}