Add client applications as submodules to main repository

- Keep main swingmusic backend code (src/, pyproject.toml, etc.)
- Add swingmusic-android as submodule
- Add swingmusic-desktop as submodule
- Add swingmusic-webclient as submodule
- Update README to reflect main backend + client apps structure
- Repository now contains complete Swing Music ecosystem in one place

.gitmodules

@@ -0,0 +1,9 @@
+[submodule "swingmusic-android"]
+	path = swingmusic-android
+	url = https://github.com/Dvorinka/swingmusic-extended-android
+[submodule "swingmusic-desktop"]
+	path = swingmusic-desktop
+	url = https://github.com/Dvorinka/swingmusic-extended-desktop
+[submodule "swingmusic-webclient"]
+	path = swingmusic-webclient
+	url = https://github.com/Dvorinka/swingmusic-extended-webclient

README.md

@@ -1,4 +1,4 @@
-# 🎵 SwingMusic Extended Backend
+# 🎵 Swing Music Extended
 
 A powerful, self-hosted music streaming backend with comprehensive features and modern architecture.
 
@@ -28,6 +28,28 @@ A powerful, self-hosted music streaming backend with comprehensive features and
 - **Lyrics Integration** - Fetch and display lyrics
 - **Last.fm Scrobbling** - Automatic scrobbling support
 
+## 📦 Client Applications
+
+This repository includes client applications as submodules:
+
+### 📱 Mobile App
+**[swingmusic-android](./swingmusic-android)** - Android mobile application
+- Modern Android app with Material Design 3
+- Offline music support
+- Cross-platform music streaming
+
+### 🖥️ Desktop App  
+**[swingmusic-desktop](./swingmusic-desktop)** - Cross-platform desktop application
+- Built with Tauri (Rust + Web)
+- Native performance with web UI
+- Windows, macOS, and Linux support
+
+### 🌐 Web Client
+**[swingmusic-webclient](./swingmusic-webclient)** - Web-based client application
+- Modern web interface
+- Browser-based music streaming
+- Responsive design
+
 ## 🚀 Quick Start
 
 ### Prerequisites