fix(host): drop the folder-dialog Description both picker modes render badly

.NET 10's modern FolderBrowserDialog renders Description as a bottom
strip above the folder input, and the 5.1 classic dialog as an unthemed
white box; the property is dropped entirely and a regression assertion
pins its absence.

packages/host/directory-picker-native/src/native-picker.ts

@@ -68,14 +68,15 @@ export async function pickNativeDirectory(
     // PowerShell 5.1's FolderBrowserDialog is hardwired to the legacy
     // SHBrowseForFolder tree; prefer pwsh and fall back only when it is absent.
     // Both hosts spawn DPI-unaware, so the script opts the process into system
-    // DPI awareness before any window is created.
+    // DPI awareness before any window is created. No Description is set: the
+    // modern dialog renders it as a bottom strip and the classic dialog as an
+    // unthemed box.
     const script = [
       "$ErrorActionPreference = 'Stop'",
       "Add-Type -TypeDefinition 'using System; using System.Runtime.InteropServices; public static class DpiAware { [DllImport(\"user32.dll\")] public static extern bool SetProcessDPIAware(); }'",
       '[DpiAware]::SetProcessDPIAware() | Out-Null',
       'Add-Type -AssemblyName System.Windows.Forms',
       '$dialog = New-Object System.Windows.Forms.FolderBrowserDialog',
-      "$dialog.Description = 'Select Workspace Directory'",
       '$dialog.ShowNewFolderButton = $true',
       '$result = $dialog.ShowDialog()',
       'if ($result -eq [System.Windows.Forms.DialogResult]::OK) {',

packages/host/directory-picker-native/tests/native-picker.spec.ts

@@ -57,6 +57,8 @@ describe('native directory picker', () => {
     const script = run.mock.calls[0]?.[1].at(-1)
     expect(script).toContain("$ErrorActionPreference = 'Stop'")
     expect(script).toContain('SetProcessDPIAware')
+    // Description renders as a bottom strip (modern) / unthemed box (classic); never set it.
+    expect(script).not.toContain('Description')
     run.mockResolvedValueOnce({ stdout: '', stderr: '' })
     await expect(pickNativeDirectory(signal(), { platform: 'win32', run })).resolves.toBeNull()
     run.mockRejectedValueOnce(failure(1, 'Add-Type failed'))