feat: implement inpainting functionality with mask handling

- Added `createMaskedPixelReplacementSource` function to handle pixel replacement using inpainting.
- Introduced `buildInpaintBundle` to prepare inpainting data including mask generation and validation.
- Created utility functions for mask operations such as `applyMaskedContentModeToRgba`, `expandRectWithinBounds`, and others for mask manipulation.
- Developed tests for inpainting preparation and mask raster utilities to ensure functionality and correctness.
- Implemented mask raster operations including inversion, feathering, blurring, and more.

view/bottom-controls/BrushControls.tsx

@@ -31,6 +31,13 @@ export function BrushControls({ tool, settings, editingMask = false, maskViewMod
         {tool === "eraser" ? <Eraser size={24} weight="regular" /> : <PaintBrush size={24} weight="regular" />}
       </span>
       <BottomControlDivider />
+      {editingMask ? (
+        <>
+          <button type="button" className={maskModeButtonClass(tool === "brush")} onClick={() => dispatch(commandIds.toolSetActive, { tool: "brush" })}>Reveal</button>
+          <button type="button" className={maskModeButtonClass(tool === "eraser")} onClick={() => dispatch(commandIds.toolSetActive, { tool: "eraser" })}>Hide</button>
+          <BottomControlDivider />
+        </>
+      ) : null}
       {tool === "brush" && !editingMask ? (
         <label className={bottomControlFieldClass()}>
           <span className={bottomControlLabelClass()}>Color</span>
@@ -91,3 +98,7 @@ export function BrushControls({ tool, settings, editingMask = false, maskViewMod
     </div>
   );
 }
+
+function maskModeButtonClass(active: boolean) {
+  return `rounded-full px-4 py-2 text-base font-medium transition ${active ? "bg-white text-black" : "bg-white/10 text-white hover:bg-white/15"}`;
+}