Fix Add Server dialog buttons hidden when SQL auth selected

MaxHeight was 700px which wasn't enough to fit the Username/Password
fields plus Connection Options plus buttons. Bumped to 850px.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: erikdarlingdata

Dashboard/AddServerDialog.xaml

@@ -2,7 +2,7 @@
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         Title="Add SQL Server"
-        SizeToContent="Height" Width="450" MaxHeight="700"
+        SizeToContent="Height" Width="450" MaxHeight="850"
         WindowStartupLocation="CenterOwner"
         ResizeMode="NoResize"
         Background="{DynamicResource BackgroundBrush}"