fix: use return instead of exit in iex mode to prevent closing the PowerShell host

scripts/install.ps1

@@ -1062,12 +1062,12 @@ try {
         if ($Upgrade) {
             Invoke-Upgrade
             Start-Sleep 3
-            exit
+            return
         }
         if ($Force -or $Source -or $SkipHub -or $InstallDir) {
             Invoke-Install
             Start-Sleep 3
-            exit
+            return
         }
         if (-not $script:STATUS_CLI_INSTALLED) {
             Write-Host ""
@@ -1076,7 +1076,7 @@ try {
         }
         Write-Host ""
         Start-Sleep 3
-        exit
+        return
     }
 
     # 交互菜单
@@ -1088,5 +1088,5 @@ try {
     Write-Err "脚本错误: $_"
     Write-Host "按 Enter 退出..."
     $null = Read-Host
-    exit 1
+    if ($isIexExecution) { return } else { exit 1 }
 }