extras/powershell_greeting: fix WezTerm logo stretch (iterm + preserveAspectRatio)

kitty-direct sends c= but no rows through ConPTY (the terminal guesses the height and stretches); the plain kitty type needs tty pixel queries that ConPTY drops. The iterm type with preserveAspectRatio=1 letterboxes any aspect ratio.

extras/powershell_greeting/J621Greeting.ps1

@@ -23,6 +23,7 @@
 #   J621_LOGO_TYPE          force a fastfetch logo type (sixel, kitty-direct, ...)
 #   J621_ALWAYS_FETCH=1     fetch even in terminals without image support
 #   J621_LOGO_WIDTH         logo width in columns (default 35)
+#   J621_LOGO_HEIGHT        iterm box height in rows (default 25)
 
 #Requires -Version 5.1
 
@@ -99,7 +100,7 @@ function Show-J621Greeting {
     $logoType = $env:J621_LOGO_TYPE
     if (-not $logoType) {
         if ($env:WT_SESSION) { $logoType = 'sixel' }
-        elseif ($env:WEZTERM_PANE) { $logoType = 'kitty-direct' }
+        elseif ($env:WEZTERM_PANE) { $logoType = 'iterm' }
     }
     $fetchImage = [bool]$logoType -or ($env:J621_ALWAYS_FETCH -eq '1')
     $ffArgs = @(Get-J621FastfetchArgs)
@@ -169,7 +170,16 @@ function Show-J621Greeting {
 
     # --- Display result ---
     if ($logoType) {
-        & fastfetch @ffArgs --logo-type $logoType --logo $tempFile --logo-width $logoWidth
+        $logoArgs = @('--logo-type', $logoType, '--logo', $tempFile, '--logo-width', $logoWidth)
+        if ($logoType -eq 'iterm') {
+            # Box + preserveAspectRatio: never stretched, whatever the aspect ratio
+            # (kitty-direct cannot do this through ConPTY: its payload has no rows).
+            $logoHeight = if ($env:J621_LOGO_HEIGHT) { $env:J621_LOGO_HEIGHT } else { '25' }
+            $logoArgs += @('--logo-height', $logoHeight, '--logo-preserve-aspect-ratio', 'true')
+        } elseif ($env:J621_LOGO_HEIGHT) {
+            $logoArgs += @('--logo-height', $env:J621_LOGO_HEIGHT)
+        }
+        & fastfetch @ffArgs @logoArgs
     } else {
         & fastfetch @ffArgs
     }