feat: add Windows computer-use plugin adapter and validation tools

tests/capture-fixture.ps1

@@ -0,0 +1,31 @@
+param([string]$Title, [string]$ReadyFile, [switch]$Cover)
+Add-Type -AssemblyName System.Windows.Forms
+Add-Type -AssemblyName System.Drawing
+$form = New-Object System.Windows.Forms.Form
+$form.Text = $Title
+$form.Size = New-Object System.Drawing.Size(500, 300)
+$form.StartPosition = 'Manual'
+$form.Location = New-Object System.Drawing.Point(100, 100)
+$form.TopMost = $true
+$form.BackColor = if ($Cover) { [System.Drawing.Color]::Magenta } else { [System.Drawing.Color]::Lime }
+$label = New-Object System.Windows.Forms.Label
+$label.Text = if ($Cover) { 'OCCLUDER - NOT TEST EVIDENCE' } else { 'ARTEMIS window capture fixture' }
+$label.Location = New-Object System.Drawing.Point(20, 25)
+$label.AutoSize = $true
+$form.Controls.Add($label)
+$button = New-Object System.Windows.Forms.Button
+$button.Text = 'Capture coordinate target'
+$button.AccessibleName = 'Capture coordinate target'
+$button.Location = New-Object System.Drawing.Point(100, 100)
+$button.Size = New-Object System.Drawing.Size(180, 50)
+$button.BackColor = [System.Drawing.Color]::Red
+$button.Add_Click({ [System.IO.File]::WriteAllText(($ReadyFile + '.clicked'), 'clicked') })
+$form.Controls.Add($button)
+$timer = New-Object System.Windows.Forms.Timer
+$timer.Interval = 120000
+$timer.Add_Tick({ $form.Close() })
+$form.Add_Shown({
+    [System.IO.File]::WriteAllText($ReadyFile, $PID.ToString())
+    $timer.Start()
+})
+try { [System.Windows.Forms.Application]::Run($form) } finally { $timer.Dispose(); $form.Dispose() }