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/fastadmin/users-list.less

@@ -0,0 +1,42 @@
+/*
+ * Component: Users List
+ * ---------------------
+ */
+.users-list {
+  &:extend(.list-unstyled);
+  > li {
+    width: 25%;
+    float: left;
+    padding: 10px;
+    text-align: center;
+    img {
+      .border-radius(50%);
+      max-width: 100%;
+      height: auto;
+    }
+    > a:hover {
+      &,
+      .users-list-name {
+        color: #999;
+      }
+    }
+  }
+}
+
+.users-list-name,
+.users-list-date {
+  display: block;
+}
+
+.users-list-name {
+  font-weight: 600;
+  color: #444;
+  overflow: hidden;
+  white-space: nowrap;
+  text-overflow: ellipsis;
+}
+
+.users-list-date {
+  color: #999;
+  font-size: 12px;
+}