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/close.less

@@ -0,0 +1,37 @@
+// stylelint-disable property-no-vendor-prefix
+
+//
+// Close icons
+// --------------------------------------------------
+
+
+.close {
+  float: right;
+  font-size: (@font-size-base * 1.5);
+  font-weight: @close-font-weight;
+  line-height: 1;
+  color: @close-color;
+  text-shadow: @close-text-shadow;
+  .opacity(.2);
+
+  &:hover,
+  &:focus {
+    color: @close-color;
+    text-decoration: none;
+    cursor: pointer;
+    .opacity(.5);
+  }
+
+  // Additional properties for button version
+  // iOS requires the button element instead of an anchor tag.
+  // If you want the anchor version, it requires `href="#"`.
+  // See https://developer.mozilla.org/en-US/docs/Web/Events/click#Safari_Mobile
+  button& {
+    padding: 0;
+    cursor: pointer;
+    background: transparent;
+    border: 0;
+    -webkit-appearance: none;
+    appearance: none;
+  }
+}