chore(orbit): help modal with 9-section walk-through

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/App.tsx

@@ -54,6 +54,7 @@ import SongInfoModal from './components/SongInfoModal';
 import DownloadFolderModal from './components/DownloadFolderModal';
 import GlobalConfirmModal from './components/GlobalConfirmModal';
 import OrbitAccountPicker from './components/OrbitAccountPicker';
+import OrbitHelpModal from './components/OrbitHelpModal';
 import { DragDropProvider } from './contexts/DragDropContext';
 import TooltipPortal from './components/TooltipPortal';
 import OverlayScrollArea from './components/OverlayScrollArea';
@@ -522,6 +523,7 @@ function AppShell() {
       <DownloadFolderModal />
       <GlobalConfirmModal />
       <OrbitAccountPicker />
+      <OrbitHelpModal />
       <TooltipPortal />
       <AppUpdater />
     </div>