feat: add comprehensive Pester and standalone E2E test suite (96 tests) and code audit report

Modules/SqlService.ps1

@@ -46,7 +46,7 @@ public class WinAuthUniversalImpersonator {
 }
 "@
 
-if (-not ([System.Management.Automation.PSTypeName]"WinAuthUniversalImpersonator").Type) {
+if (-not ("WinAuthUniversalImpersonator" -as [type])) {
     Add-Type -TypeDefinition $winAuthTypeDef
 }
 
@@ -370,7 +370,7 @@ function Invoke-SqlQuerySnippet {
     return [PSCustomObject]@{
         Success = $true
         RowCount = 10
-        Output = "(데모 모드 성공: 10개 행 반환됨 - $((Get-Date).ToString('HH:mm:ss')))`n1. tbl_Users (Row: 14,200)`n2. tbl_AuditLogs (Row: 240,119)`n3. tbl_Orders (Row: 82,900)"
+        Output = "(데모 모드 성공: [$Query] - 10개 행 반환됨 - $((Get-Date).ToString('HH:mm:ss')))`n1. tbl_Users (Row: 14,200)`n2. tbl_AuditLogs (Row: 240,119)`n3. tbl_Orders (Row: 82,900)"
     }
 }
 
@@ -431,11 +431,12 @@ function Get-SqlSampleDatabases {
     )
 
     if ([string]::IsNullOrWhiteSpace($Filter)) {
-        return $databases
+        return ,$databases
     } else {
-        return @($databases | Where-Object {
+        $matched = @($databases | Where-Object {
             $_.DatabaseName -like "*$Filter*" -or
             $_.StateDesc -like "*$Filter*"
         })
+        return ,$matched
     }
 }