Initial commit: Phase 1 – Projektstruktur, DB-Schema, Core-API

- FastAPI-Backend mit vollständiger ABS v2.x API-Kompatibilität
- SQLAlchemy-Models: User, Library, LibraryItem, BookFile, Chapter,
  Podcast, PodcastEpisode, MediaProgress, Bookmark, PlaybackSession
- Auth: JWT-Login (/login, /logout, /api/authorize)
- Library + Items Endpoints inkl. camelCase ABS-Response-Format
- HLS-Streaming via FFmpeg (POST /api/items/:id/play, Session-Sync)
- Me/Progress Endpoints + Lesezeichen
- User-Management + Server-Settings (Admin)
- Library-Scanner (MP3/WAV Discovery, Hintergrund-Task)
- File Watcher (watchdog, 30s Debounce)
- Matching-Skelett (MusicBrainz, OpenLibrary, Google Books – Phase 5)
- Docker-Setup: backend (Python 3.12+FFmpeg), frontend (React/Vite),
  nginx Reverse-Proxy auf Port 3000
- setup.sh: Installiert Docker auf Debian/Ubuntu, richtet .env ein

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

frontend/src/main.tsx

@@ -0,0 +1,10 @@
+import React from 'react'
+import ReactDOM from 'react-dom/client'
+import App from './App'
+import './index.css'
+
+ReactDOM.createRoot(document.getElementById('root')!).render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>
+)