A frame with borders tiles unless told to stretch

The fill of a sliced frame defaulted to `Stretch`. It is `Repeat` now, and the Fill dropdown lists
`Repeat` first.

The saved document keeps writing only the fill that differs from the default, so the key it
carries is now `stretch`, and a frame without it repeats. A frame saved before with the key
absent and meaning stretch would therefore tile; none of the stored projects has one - both sliced
frames on the server carry `fill: "repeat"` explicitly, so they draw as before.

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

src/core/model/texture.ts

@@ -117,7 +117,7 @@ function refFor(asset: TextureAsset, frame: TextureFrame | null): TextureRef | n
 }
 
 export const NO_BORDERS: FrameBorders = { left: 0, top: 0, right: 0, bottom: 0 };
-export const DEFAULT_FILL: FrameFill = 'stretch';
+export const DEFAULT_FILL: FrameFill = 'repeat';
 
 /** Whole pixels of the frame that must stay between two opposite borders (see `normalizeBorders`). */
 export const MIN_SLICE_MIDDLE = 1;
@@ -127,7 +127,7 @@ export function frameBorders(frame: TextureFrame): FrameBorders {
 }
 
 export function frameFill(frame: TextureFrame): FrameFill {
-  return frame.fill === 'repeat' ? 'repeat' : DEFAULT_FILL;
+  return frame.fill === 'stretch' ? 'stretch' : DEFAULT_FILL;
 }
 
 export function hasBorders(border: FrameBorders): boolean {
@@ -181,9 +181,9 @@ export function setFrameSlice(frame: TextureFrame, slice: FrameSlice): void {
   const border = normalizeBorders(slice.border, frame.w, frame.h);
   if (hasBorders(border)) frame.border = border;
   else delete frame.border;
-  // Kept even without borders: a fill chosen before the borders are dragged would otherwise
-  // snap back to "stretch" under the hand that just set it.
-  if (slice.fill === 'repeat') frame.fill = 'repeat';
+  // Only the fill that differs from `DEFAULT_FILL` is written. Kept even without borders: a fill
+  // chosen before the borders are dragged would otherwise snap back under the hand that just set it.
+  if (slice.fill !== DEFAULT_FILL) frame.fill = slice.fill;
   else delete frame.fill;
 }