Update README with full project overview

Covers features, module structure, Docker setup, env vars,
dev workflow and first-launch instructions.

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

README.md

@@ -1,20 +1,106 @@
 # NovaSonic
 
-A self-hosted music streaming PWA for Navidrome / Subsonic-compatible backends.
+A self-hosted music streaming PWA for Navidrome / Subsonic-compatible servers.  
+Built with Vite + vanilla ES modules, served via nginx in Docker.
 
-## Stack
+---
 
-- `index.html` — app shell
+## Features
-- `styles.css` — all styles
-- `app.js` — frontend logic
-- `sw.js` — service worker (offline caching)
 
-## Setup
+- Stream music from your Navidrome / Subsonic library
+- Browse artists, albums, playlists, starred tracks and random picks
+- Queue management with shuffle, repeat (all / once) and radio mode (endless random)
+- Now Playing overlay with swipe-to-dismiss and lock screen media controls (Android/iOS)
+- iTunes / Last.fm integration — charts, global search, 30s previews, recommendations
+- Download tracks from YouTube/SoundCloud via yt-dlp directly into your music library
+- Duplicate detection — skips tracks that already exist on the server
+- Edit playlists (name, description, cover art, public toggle)
+- PWA — installable, offline-capable via service worker
+- Dark theme, mobile-first responsive layout
 
-Point the app at your Navidrome server URL on first launch.
+---
 
-## Docker
+## Project Structure
+
+```
+Music_App/
+├── src/                       # ES modules (Vite entry)
+│   ├── state.js               # Shared mutable state (S object)
+│   ├── utils.js               # md5, esc, formatDur, toast
+│   ├── api.js                 # Subsonic API, Navidrome REST, iTunes API
+│   ├── player.js              # Playback, transport, queue, media session, preview
+│   ├── views.js               # Navigation, page loaders, card makers, search
+│   ├── ui.js                  # Modals, overlays, sidebar, settings, context menu
+│   ├── pwa.js                 # Service worker registration + update banner
+│   └── main.js                # App init, audio wiring, window globals
+├── public/                    # Static assets (copied as-is to dist/)
+│   ├── sw.js                  # Service worker
+│   ├── manifest.json          # PWA manifest
+│   ├── icon.svg               # App icon
+│   └── config.js              # Runtime config placeholder (generated by Docker)
+├── backend/
+│   └── novasonic-server.js    # Node.js download backend (yt-dlp + ffmpeg)
+├── index.html                 # App shell + Vite entry point
+├── styles.css                 # All styles
+├── vite.config.js
+├── Dockerfile                 # Multi-stage: Node build → nginx serve
+├── docker-compose.yml
+├── nginx.conf
+└── docker-entrypoint.sh       # Injects NS_SERVER_URL / NS_BACKEND_URL at startup
+```
+
+---
+
+## Docker Setup
+
+### Frontend only
 
 ```bash
 docker compose up -d
 ```
+
+Environment variables (set in `docker-compose.yml` or via `-e`):
+
+| Variable | Description |
+|---|---|
+| `NS_SERVER_URL` | Pre-fills the Navidrome server URL on the login screen |
+| `NS_BACKEND_URL` | Pre-fills the download backend URL |
+
+### With download backend
+
+The backend requires `yt-dlp` and `ffmpeg`. A separate `docker-compose.yml` lives in `backend/`.
+
+```bash
+cd backend
+docker compose up -d
+```
+
+Environment variables for the backend:
+
+| Variable | Default | Description |
+|---|---|---|
+| `PORT` | `3700` | Port the backend listens on |
+| `MUSIC_PATH` | `/music` | Path to your Navidrome music folder (mount as volume) |
+| `AUDIO_FMT` | `mp3` | Output format (`mp3`, `flac`, `opus`, …) |
+| `AUDIO_QUALITY` | `0` | yt-dlp audio quality (0 = best) |
+| `MAX_PARALLEL` | `2` | Maximum concurrent downloads |
+
+---
+
+## Development
+
+```bash
+npm install
+npm run dev      # Vite dev server with HMR
+npm run build    # Production build → dist/
+npm run preview  # Preview the production build locally
+```
+
+---
+
+## First Launch
+
+1. Open the app in a browser
+2. Enter your Navidrome server URL, username and password
+3. Optionally add a Last.fm API key (Settings) for recommendations and similar artists
+4. Optionally add the backend URL (Settings) to enable yt-dlp downloads