Stop drawing a hover ring on a device that cannot hover

A cell drew a 1px ring while the pointer was over it, in the same colour
as the 2px ring that means "selected". On a tablet there is no pointer,
and `has-hover` is not the harmless no-op that implies: Slint raises it
on a touch press and lowers it on the `Exit` that normally follows the
release — but the release that ends a pinch carries no `Exit` at all,
and neither does a finger lifting while a second one is still down.

So resizing the thumbnails, which is a pinch, left a ring around
whichever cell each finger had come down on. The grid then showed boxes
around photographs that were not selected, a pixel thinner than the ones
that were, with nothing to tell them apart.

Hover chrome has no meaning once there has been a finger, so it is not
drawn: the same `touched` latch the rating strip already keys off.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

ui/dr-ui/ui/library.slint

@@ -2976,7 +2976,19 @@ export component LibraryGrid inherits Rectangle {
                     // photograph, which is exactly the wrong feedback for a
                     // gesture whose whole job is to say "this one". One
                     // treatment, drawn inside, in one place.
-                    border-width: cell-touch.has-hover ? 1px : 0px;
+                    //
+                    // **Not drawn at all once there has been a finger.** A
+                    // hand has no hover to give, so on a tablet this ring can
+                    // only ever be wrong — and it is wrong in the worst way,
+                    // because it is the selection ring's own colour a pixel
+                    // thinner. `has-hover` is not reliably cleared on touch:
+                    // a release normally brings an `Exit` with it, but the one
+                    // that ends a pinch does not, so every pinch to resize the
+                    // thumbnails left a ring around whichever cell a finger
+                    // happened to have started on. The grid then showed boxes
+                    // around photographs that were not selected, with no way
+                    // to tell them from ones that were. See `touched`.
+                    border-width: cell-touch.has-hover && !root.touched ? 1px : 0px;
                     border-color: Theme.selected-ring;
                     clip: true;