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/font-awesome/less/rotated-flipped.less

@@ -0,0 +1,20 @@
+// Rotated & Flipped Icons
+// -------------------------
+
+.@{fa-css-prefix}-rotate-90  { .fa-icon-rotate(90deg, 1);  }
+.@{fa-css-prefix}-rotate-180 { .fa-icon-rotate(180deg, 2); }
+.@{fa-css-prefix}-rotate-270 { .fa-icon-rotate(270deg, 3); }
+
+.@{fa-css-prefix}-flip-horizontal { .fa-icon-flip(-1, 1, 0); }
+.@{fa-css-prefix}-flip-vertical   { .fa-icon-flip(1, -1, 2); }
+
+// Hook for IE8-9
+// -------------------------
+
+:root .@{fa-css-prefix}-rotate-90,
+:root .@{fa-css-prefix}-rotate-180,
+:root .@{fa-css-prefix}-rotate-270,
+:root .@{fa-css-prefix}-flip-horizontal,
+:root .@{fa-css-prefix}-flip-vertical {
+  filter: none;
+}