feat: Audiobookshelf integration — browse, stream, chapters, sleep timer

- src/abs.js: full ABS API client + player engine
  - Login/token auth, library browsing, search
  - Playback session API (multi-file book support via startOffset)
  - Progress sync to ABS every 30s and on pause
  - Chapter navigation (prev/next/seek-to), ±10s / ±30s skip
  - Speed control (0.75–2×), sleep timer with countdown
- index.html: sidebar nav, audiobooks/detail pages, full-screen player overlay,
  ABS settings section (URL + credentials + library picker)
- state.js: abs + absPlayer state objects
- views.js: navigate() handles 'audiobooks' and 'abs-book-detail'
- styles.css: book grid, detail page, player overlay, pickers

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/main.js

@@ -18,6 +18,14 @@ import {
   loadRandom,
 } from './views.js';
 import { loadSpotifyImporter, resolveSpotifyLink, clearSpotifyPreview, spotifyDlAll } from './spotify.js';
+import {
+  absInitFromStorage, absOpenSettings, absConnectSettings, absSetLibrary, absDisconnect,
+  absPlayItem, absTogglePlay, absSeek, absSkipSecs, absNextChapter, absPrevChapter,
+  absSetSpeed, absSleepIn, absOpenPlayer, absClosePlayer, absToggleChapters,
+  absToggleSpeedPicker, absToggleSleepPicker, absSeekToChapter, absProgDown, absProgMove,
+  absProgUp, loadAbsBooks, absOpenBook, loadAbsBookDetail, absPlayChapter,
+  absLoadSettingsLibraries,
+} from './abs.js';
 import {
   openNowPlaying, closeNowPlaying, switchNpTab, npGoArtist, npGoAlbum,
   openNpMenu, closeNpMenu,
@@ -74,6 +82,11 @@ function disconnect() {
 async function startApp() {
   document.getElementById('setup-screen').style.display='none';
   document.getElementById('app').style.display='flex';
+  absInitFromStorage();
+  if (S.abs.token) {
+    document.getElementById('nav-abs-section').style.display = '';
+    absLoadSettingsLibraries();
+  }
   if(_navLoad() && S._navCursor >= 0 && S._navStack[S._navCursor]) {
     const last = S._navStack[S._navCursor];
     S._navJumping = true;
@@ -250,4 +263,16 @@ Object.assign(window, {
   toggleNotifPanel, deleteNotif, clearNotifs, _notifNavigate, _pickTheme,
   // App
   doConnect, disconnect,
+  // Audiobookshelf
+  absPlayItem, absTogglePlay, absSeek, absSkipSecs, absNextChapter, absPrevChapter,
+  absSetSpeed, absSleepIn, absOpenPlayer, absClosePlayer, absToggleChapters,
+  absToggleSpeedPicker, absToggleSleepPicker, absSeekToChapter,
+  absProgDown, absProgMove, absProgUp,
+  absOpenBook, absPlayChapter, absConnectSettings, absSetLibrary, absDisconnect,
+  absOnSearch: (val) => {
+    clearTimeout(window._absSearchTimer);
+    window._absSearchTimer = setTimeout(() => {
+      if (S.abs.currentLibraryId) loadAbsBooks(S.abs.currentLibraryId, val.trim());
+    }, 350);
+  },
 });