refactor(utils): group utils/ files into topic folders (Phase L, part 1) (#689)

111 of 122 top-level src/utils/ files move into 16 topic folders (audio,
cache, cover, share, server, playback, playlist, deviceSync, waveform,
mix, format, export, changelog, ui, perf, componentHelpers). True
singletons with no cluster stay at the utils/ root.

Pure file-move: a path-aware codemod rewrote 539 relative-import
specifiers across 275 files; no logic touched. The hot-path coverage
gate list (.github/frontend-hot-path-files.txt) is updated to the new
paths for the 11 gated utils files — a mechanical consequence of the
move, not a CI change. tsc is green.

src/app/AppShell.tsx

@@ -50,11 +50,11 @@ import { usePlayerStore } from '../store/playerStore';
 import { useThemeStore } from '../store/themeStore';
 import { useFontStore } from '../store/fontStore';
 import { useEqStore } from '../store/eqStore';
-import { usePerfProbeFlags } from '../utils/perfFlags';
+import { usePerfProbeFlags } from '../utils/perf/perfFlags';
 import {
   persistSidebarCollapsed,
   readInitialSidebarCollapsed,
-} from '../utils/appShellHelpers';
+} from '../utils/componentHelpers/appShellHelpers';
 
 /**
  * The main webview's persistent layout: titlebar (Linux only) + sidebar +

src/app/MainApp.tsx

@@ -2,7 +2,7 @@ import { initAudioListeners } from '../store/initAudioListeners';
 import { lazy, Suspense, useEffect, useState } from 'react';
 import { BrowserRouter, Route, Routes } from 'react-router-dom';
 import { invoke } from '@tauri-apps/api/core';
-import { showToast } from '../utils/toast';
+import { showToast } from '../utils/ui/toast';
 import { WindowVisibilityProvider } from '../hooks/useWindowVisibility';
 import { DragDropProvider } from '../contexts/DragDropContext';
 import PasteClipboardHandler from '../components/PasteClipboardHandler';
@@ -69,7 +69,7 @@ export default function MainApp() {
   const handleExport = async (since: number) => {
     setExportPickerOpen(false);
     try {
-      const { exportNewAlbumsImage } = await import('../utils/exportNewAlbums');
+      const { exportNewAlbumsImage } = await import('../utils/export/exportNewAlbums');
       const result = await exportNewAlbumsImage(since);
       if (result) {
         const files = result.paths.length > 1 ? ` (${result.paths.length} Dateien)` : '';

src/app/MiniPlayerApp.test.tsx

@@ -22,7 +22,7 @@ vi.mock('../store/fontStore', () => ({
 vi.mock('../store/keybindingsStore', () => ({
   useKeybindingsStore: { persist: { rehydrate: keybindingsRehydrate } },
 }));
-vi.mock('../utils/perfFlags', () => ({
+vi.mock('../utils/perf/perfFlags', () => ({
   usePerfProbeFlags: () => ({ disableTooltipPortal: true }),
 }));
 vi.mock('../i18n', () => ({

src/app/MiniPlayerApp.tsx

@@ -7,7 +7,7 @@ import FpsOverlay from '../components/FpsOverlay';
 import { useThemeStore } from '../store/themeStore';
 import { useFontStore } from '../store/fontStore';
 import { useKeybindingsStore } from '../store/keybindingsStore';
-import { usePerfProbeFlags } from '../utils/perfFlags';
+import { usePerfProbeFlags } from '../utils/perf/perfFlags';
 import i18n from '../i18n';
 
 /**