feat: add grid-inventory

src/samples/slay-the-spire-like/grid-inventory/index.ts

@@ -0,0 +1,13 @@
+export type { CellCoordinate, GridInventory, InventoryItem, PlacementResult } from './types';
+export {
+    createGridInventory,
+    flipItem,
+    getAdjacentItems,
+    getItemAtCell,
+    getOccupiedCellSet,
+    moveItem,
+    placeItem,
+    removeItem,
+    rotateItem,
+    validatePlacement,
+} from './transform';