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/nuget/MyGet.ps1

@@ -0,0 +1,8 @@
+$nuget = $env:NuGet
+
+# parse the version number out of package.json
+$bsversion = ((Get-Content $env:SourcesPath\package.json) -join "`n" | ConvertFrom-Json).version
+
+# create packages
+& $nuget pack "nuget\bootstrap.nuspec" -Verbosity detailed -NonInteractive -NoPackageAnalysis -BasePath $env:SourcesPath -Version $bsversion
+& $nuget pack "nuget\bootstrap.less.nuspec" -Verbosity detailed -NonInteractive -NoPackageAnalysis -BasePath $env:SourcesPath -Version $bsversion