feat: 引入多环境配置支持，通过 .env.dev 和 .env.prod 文件管理不同环境配置，并更新 main.go 以加载对应配置。

switch_env.ps1

@@ -0,0 +1,20 @@
+param (
+    [string]$env = "dev"
+)
+
+$source = ".env.$env"
+$dest = ".env"
+
+if (Test-Path $source) {
+    Copy-Item -Path $source -Destination $dest -Force
+    Write-Host "Success: Switched to $env environment ($source -> $dest)"
+    
+    # Simple check to see if environment content matches
+    $content = Get-Content $dest -TotalCount 10
+    Write-Host "Current Config Preview:"
+    $content | Select-String "ENVIRONMENT"
+    $content | Select-String "DB_HOST"
+} else {
+    Write-Error "Error: Source file $source does not exist."
+    Write-Host "Usage: ./switch_env.ps1 [dev|prod]"
+}