feat(materials): free rotate session overlays and show save progress

Match NPC drag-to-rotate on the material frame during playback, and change the add/edit Save button to Saving… while import runs.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/renderer/materials/MaterialsApp.tsx

@@ -90,7 +90,12 @@ export function MaterialsApp() {
         onSelect={onSelect}
         activeMaterialId={activeId}
         onTileActivate={(id) => {
-          void overlayApi.dispatch({ kind: 'toggle', materialId: id });
+          const mat = materials.find((m) => m.id === id);
+          void overlayApi.dispatch({
+            kind: 'toggle',
+            materialId: id,
+            rotationDeg: mat?.rotationDeg ?? 0,
+          });
         }}
         toolbar={
           <>