Update README.md to include project description, developer documentation links, and license information.

src/MrGameEng.Audio/AudioManager.cs

@@ -0,0 +1,46 @@
+using Microsoft.Xna.Framework.Audio;
+using MrGameEng.Core;
+
+namespace MrGameEng.Audio;
+
+/// <summary>
+/// Sound-effect playback with a module-level volume, plus the <see cref="Music"/> player.
+/// Registered as a service via <c>context.UseAudio()</c>.
+/// </summary>
+public sealed class AudioManager : IDisposable
+{
+    /// <summary>The streaming music player.</summary>
+    public MusicPlayer Music { get; } = new();
+
+    /// <summary>Volume multiplier applied to every sound effect, 0..1.</summary>
+    public float SoundVolume
+    {
+        get => _soundVolume;
+        set => _soundVolume = Math.Clamp(value, 0f, 1f);
+    }
+
+    private float _soundVolume = 1f;
+
+    /// <summary>Plays a sound effect (fire and forget).</summary>
+    /// <param name="sound">The loaded sound effect.</param>
+    /// <param name="volume">Per-play volume 0..1, multiplied with <see cref="SoundVolume"/>.</param>
+    /// <param name="pitch">Pitch offset in octaves, -1..1.</param>
+    /// <param name="pan">Stereo pan, -1 (left) .. 1 (right).</param>
+    public void Play(SoundEffect sound, float volume = 1f, float pitch = 0f, float pan = 0f) =>
+        sound.Play(Math.Clamp(volume, 0f, 1f) * _soundVolume, pitch, pan);
+
+    /// <inheritdoc />
+    public void Dispose() => Music.Dispose();
+}
+
+/// <summary>Wires the audio module into the engine.</summary>
+public static class AudioEngineExtensions
+{
+    /// <summary>Creates the <see cref="AudioManager"/> and registers it as a service. Call once at startup.</summary>
+    public static AudioManager UseAudio(this EngineContext context)
+    {
+        var manager = new AudioManager();
+        context.Services.Add(manager);
+        return manager;
+    }
+}