fix(gallery): force a follow-up pulse after a large grid relayout

Clearing a search filter that had narrowed the grid to a handful of rows
swaps in a much longer item list in one go. Some of VirtualFlow's newly
realised GalleryRowCells were laid out (thumbnail decode requested) but
not actually painted until an unrelated later pulse caught up -- moving
the mouse only "fixed" it because Scene's picking machinery forces a
synchronous CSS+layout pass before hit-testing. Scheduling
rows.requestLayout() on a fresh Platform.runLater pulse reproduces that
same forced pass without needing real input, the same trick already used
elsewhere in this class (pulseCardOnceSettled, hookNativeScrollBar).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/main/java/org/icroco/pholio/ui/view/gallery/ThumbnailGalleryPane.java

@@ -499,6 +499,16 @@ public class ThumbnailGalleryPane extends StackPane implements Disposable {
         List<GalleryRow> grouped = GalleryRow.chunk(sorted, availableWidth, thumbnailHeight, SPACING, DATE_SPACING,
                                                     date -> date == null ? i18n.get("gallery.unknownDate") : i18n.formatDate(date, headerFormat));
         rows.getItems().setAll(grouped);
+        // A relayout that swaps in a much longer item list in one go (typically: clearing a search filter
+        // that had narrowed the grid down to a handful of rows) can leave some of VirtualFlow's newly
+        // realised cells laid out but not actually painted — their GalleryRowCell.renderPhotos already ran,
+        // async thumbnail decodes already requested, but nothing visible until some later, unrelated pulse
+        // catches it up; moving the mouse "fixes" it only because Scene's own picking machinery forces a
+        // synchronous CSS+layout pass before hit-testing. requestLayout() on a fresh pulse (never this one,
+        // already mid-reflow) reproduces that same forced pass without needing real input — the same
+        // "VirtualFlow needs another pulse to settle" trick #reveal/#pulseCardOnceSettled and
+        // #hookNativeScrollBar already rely on Platform.runLater for elsewhere in this class.
+        Platform.runLater(rows::requestLayout);
         // Only when height/quality actually changed since the last relayout: a change small enough to
         // leave the column count (and so every GalleryRow's own grouping) unchanged produces a
         // structurally-equal item list — nothing for the ListView to notice on its own — while every