Add generationStatus and match3d/runtime fixes

Introduce persistent generationStatus to work summaries (puzzle & match3d) and propagate generation recovery rules across docs and frontend/backends so "generating" is restored from server-side work summary rather than ephemeral front-end notices. Update API server image/asset handling (improve match3d material sheet green/alpha decontamination and promote generatedItemAssets background fields) and add runtime improvements: alpha-based hotspot hit-testing, tray insertion/three-match animation behavior, and session re-read on client-side VectorEngine timeouts/lock-screen interruptions. Many docs, tests and related frontend modules updated/added to reflect these contract and behavior changes.

src/components/custom-world-home/creationWorkShelf.ts

@@ -238,13 +238,19 @@ export function buildCreationWorkShelfItems(params: {
   ]
     .map((item) => {
       const state = getItemState?.(item);
+      const persistedIsGenerating = isPersistedCreationWorkGenerating(item);
       return state
         ? {
             ...item,
-            isGenerating: state.isGenerating,
+            isGenerating: Boolean(state.isGenerating || persistedIsGenerating),
             hasUnreadUpdate: state.hasUnreadUpdate,
           }
-        : item;
+        : persistedIsGenerating
+          ? {
+              ...item,
+              isGenerating: true,
+            }
+          : item;
     })
     .sort(
       (left, right) =>
@@ -793,6 +799,17 @@ function buildPuzzleWorkShelfActions(
   };
 }
 
+function isPersistedCreationWorkGenerating(item: CreationWorkShelfItem) {
+  switch (item.source.kind) {
+    case 'match3d':
+      return item.source.item.generationStatus === 'generating';
+    case 'puzzle':
+      return item.source.item.generationStatus === 'generating';
+    default:
+      return false;
+  }
+}
+
 function buildRpgWorkShelfActions(
   item: CustomWorldWorkSummary,
   adapter: RpgWorkShelfAdapter,