fix(ui): improve dragging activation

- delay of 250ms
- prevent gallery images from accidentally activating native drag and drop

invokeai/frontend/web/src/app/components/ImageDnd/ImageDndContext.tsx

@@ -40,11 +40,11 @@ const ImageDndContext = (props: ImageDndContextProps) => {
   );
 
   const mouseSensor = useSensor(MouseSensor, {
-    activationConstraint: { distance: 15 },
+    activationConstraint: { delay: 250, tolerance: 5 },
   });
 
   const touchSensor = useSensor(TouchSensor, {
-    activationConstraint: { distance: 15 },
+    activationConstraint: { delay: 250, tolerance: 5 },
   });
   // TODO: Use KeyboardSensor - needs composition of multiple collisionDetection algos
   // Alternatively, fix `rectIntersection` collection detection to work with the drag overlay

invokeai/frontend/web/src/features/gallery/components/HoverableImage.tsx

@@ -279,6 +279,7 @@ const HoverableImage = memo((props: HoverableImageProps) => {
               objectFit={
                 shouldUseSingleGalleryColumn ? 'contain' : galleryImageObjectFit
               }
+              draggable={false}
               rounded="md"
               src={thumbnail_url || image_url}
               fallback={<FaImage />}