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/scss/_bordered-pulled.scss

@@ -0,0 +1,25 @@
+// Bordered & Pulled
+// -------------------------
+
+.#{$fa-css-prefix}-border {
+  padding: .2em .25em .15em;
+  border: solid .08em $fa-border-color;
+  border-radius: .1em;
+}
+
+.#{$fa-css-prefix}-pull-left { float: left; }
+.#{$fa-css-prefix}-pull-right { float: right; }
+
+.#{$fa-css-prefix} {
+  &.#{$fa-css-prefix}-pull-left { margin-right: .3em; }
+  &.#{$fa-css-prefix}-pull-right { margin-left: .3em; }
+}
+
+/* Deprecated as of 4.4.0 */
+.pull-right { float: right; }
+.pull-left { float: left; }
+
+.#{$fa-css-prefix} {
+  &.pull-left { margin-right: .3em; }
+  &.pull-right { margin-left: .3em; }
+}