cleanup: remove unused groupAssociatedFiles state

Grouping is now driven entirely by the rawStatus filter (GroupVariants
or migrated RawOverNonRaw). The separate boolean toggle had no UI and
defaulted to false, so it was dead code.

Author: EnTeQuAk

src/App.tsx

@@ -250,7 +250,6 @@ function App() {
     rawStatus: RawStatus.All,
   });
   const [supportedTypes, setSupportedTypes] = useState<SupportedTypes | null>(null);
-  const [groupAssociatedFiles, setGroupAssociatedFiles] = useState(false);
   const [groupPreferredType, setGroupPreferredType] = useState<GroupPreference>('raw');
   const [selectedImage, setSelectedImage] = useState<SelectedImage | null>(null);
   const selectedImagePathRef = useRef<string | null>(null);
@@ -1044,8 +1043,7 @@ function App() {
   };
 
   const isGroupingActive = filterCriteria.rawStatus === RawStatus.GroupVariants ||
-    filterCriteria.rawStatus === RawStatus.RawOverNonRaw || // migration: treat old setting as grouping
-    groupAssociatedFiles;
+    filterCriteria.rawStatus === RawStatus.RawOverNonRaw; // migration: treat old setting as grouping
 
   const groupingResult: GroupingResult | null = useMemo(() => {
     if (!isGroupingActive) return null;
@@ -1577,9 +1575,6 @@ function App() {
         if (settings?.waveformHeight !== undefined) {
           setWaveformHeight(settings.waveformHeight);
         }
-        if (typeof settings?.groupAssociatedFiles === 'boolean') {
-          setGroupAssociatedFiles(settings.groupAssociatedFiles);
-        }
         if (settings?.groupPreferredType) {
           setGroupPreferredType(settings.groupPreferredType);
         }
@@ -1706,17 +1701,13 @@ function App() {
     if (isInitialMount.current || !appSettings) {
       return;
     }
-    if (
-      appSettings.groupAssociatedFiles !== groupAssociatedFiles ||
-      appSettings.groupPreferredType !== groupPreferredType
-    ) {
+    if (appSettings.groupPreferredType !== groupPreferredType) {
       handleSettingsChange({
         ...appSettings,
-        groupAssociatedFiles,
         groupPreferredType,
       });
     }
-  }, [groupAssociatedFiles, groupPreferredType, appSettings, handleSettingsChange]);
+  }, [groupPreferredType, appSettings, handleSettingsChange]);
 
   useEffect(() => {
     if (!appSettings?.adaptiveEditorTheme || !selectedImage) {