Sweep out the group-card navigation nothing reaches any more

src/DodoSSH.Client.App/App.axaml

@@ -713,7 +713,7 @@
       chosen card that also drew an accent outline would be indistinguishable from the selected one, and the
       question "which of these is the drawer showing" would have no answer. Declared after that rule anyway,
       because it sets the same Background and Avalonia settles two matching rules by declaration order —
-      the trap this file records for Button.tab, Border.rowmark and the drop target below.
+      the trap this file records for Button.tab and Border.rowmark.
     -->
     <Style Selector="Border.tile.chosen">
       <Setter Property="Background" Value="{StaticResource Active}" />
@@ -990,34 +990,6 @@
       <Setter Property="Foreground" Value="{StaticResource AccentInk}" />
     </Style>
 
-    <!--
-      The group card a host is about to be dropped on. A wash rather than the accent strip a selection
-      carries, because it is not a selection: it says "let go here", it lasts as long as the pointer is over
-      the card, and it has to be legible on top of whatever that card already looks like — including the
-      selected one, which is the group the grid is currently narrowed to and so often the one being dragged
-      onto.
-
-      Painted on the tile rather than on the item's own presenter, which is where this used to go when the
-      target was a full-width heading. A wash behind a 10-pixel-rounded tile is a square of colour with the
-      card floating on it — the same four grey corners the tiles list clears the theme's own hover and
-      selection brushes to avoid. Declared after that rule and after the selected-tile rule, because
-      Avalonia has no specificity and settles two matching rules by declaration order.
-
-      ◆ THE DOUBLED BORDER IS THE MARK, not the fill, and that is what the move to the tile forced. The fill
-      a selected tile already carries is the strongest one this palette has, so a target that only filled
-      would be invisible on the card the grid is narrowed to — which is the card a host most often has to be
-      dragged off, into another group. Two pixels of accent is legible on both.
-
-      Set from the code-behind rather than by a binding, for the reason the whole gesture is code: the rows
-      are rebuilt from scratch on every filter keystroke and every sync pass, so a flag on the view model
-      would be state the list throws away halfway through the drag. See HostsScreen.axaml.cs.
-    -->
-    <Style Selector="ListBoxItem.droptarget Border.tile">
-      <Setter Property="Background" Value="{StaticResource Active}" />
-      <Setter Property="BorderBrush" Value="{StaticResource Accent}" />
-      <Setter Property="BorderThickness" Value="2" />
-    </Style>
-
     <!--
       A context menu, in this window's palette rather than the theme's. The Fluent default is a lighter grey
       than anything else here, which on a near-black chrome reads as a dialog from another application.