fix: Ctrl-deselecting scan result jumps to previous selected row

When the current item is deselected via Ctrl+click, fall back to
the last remaining selected item instead of staying on the
deselected row.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

main.py

@@ -973,9 +973,16 @@ class ScanResultsPanel(QWidget):
         return ""
 
     def _on_selection_changed(self, table: QTableWidget) -> None:
+        selected = table.selectedItems()
         cur = table.currentItem()
-        if cur is not None:
+        # If current item was deselected, fall back to last selected row
-            start = table.item(cur.row(), 0).data(Qt.ItemDataRole.UserRole + 1)
+        if cur is not None and cur.isSelected():
+            row = cur.row()
+        elif selected:
+            row = selected[-1].row()
+        else:
+            return
+        start = table.item(row, 0).data(Qt.ItemDataRole.UserRole + 1)
         if start is not None:
             self.seek_requested.emit(float(start))