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-select/js/i18n/defaults-en_US.js

@@ -0,0 +1,23 @@
+/*
+ * Translated default messages for bootstrap-select.
+ * Locale: EN (English)
+ * Region: US (United States)
+ */
+(function ($) {
+  $.fn.selectpicker.defaults = {
+    noneSelectedText: 'Nothing selected',
+    noneResultsText: 'No results match {0}',
+    countSelectedText: function (numSelected, numTotal) {
+      return (numSelected == 1) ? "{0} item selected" : "{0} items selected";
+    },
+    maxOptionsText: function (numAll, numGroup) {
+      return [
+        (numAll == 1) ? 'Limit reached ({n} item max)' : 'Limit reached ({n} items max)',
+        (numGroup == 1) ? 'Group limit reached ({n} item max)' : 'Group limit reached ({n} items max)'
+      ];
+    },
+    selectAllText: 'Select All',
+    deselectAllText: 'Deselect All',
+    multipleSeparator: ', '
+  };
+})(jQuery);