Autotiles are a new asset type with a tab that shows every tile of the floor (2x3) or wall (2x2) block and an animated sample pattern (#118)

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

src/editor/state.ts

@@ -523,6 +523,13 @@ export class EditorState {
     return findAssetOf(this.project, s.assetId, 'animation')?.id ?? null;
   }
 
+  /** The autotile the selection refers to; only the asset itself, it has nothing inside to pick. */
+  get selectedAutotileId(): string | null {
+    const s = this.selection;
+    if (s?.kind !== 'asset') return null;
+    return findAssetOf(this.project, s.assetId, 'autotile')?.id ?? null;
+  }
+
   /** The timeline row the selection is about; undefined when it is about something else. */
   get selectedTrackId(): string | undefined {
     return this.selection?.kind === 'track' ? this.selection.trackId : undefined;