feat: add NuGet and Godot distribution

DotNet~/Runtime/ShrinkModContext.cs

@@ -0,0 +1,25 @@
+#nullable enable
+
+using System;
+using System.Collections.Generic;
+
+namespace ShrinkModFramework;
+
+public sealed class ShrinkModContext
+{
+    private readonly Dictionary<Type, object> _services = new();
+    public ShrinkModContext(string modDirectory) => ModDirectory = modDirectory ?? throw new ArgumentNullException(nameof(modDirectory));
+    public string ModDirectory { get; }
+    public void RegisterService<T>(T service) where T : class => _services[typeof(T)] = service ?? throw new ArgumentNullException(nameof(service));
+    public bool TryGetService<T>(out T? service) where T : class
+    {
+        service = _services.TryGetValue(typeof(T), out var value) ? value as T : null;
+        return service != null;
+    }
+    public T GetRequiredService<T>() where T : class => TryGetService<T>(out var value) ? value! : throw new InvalidOperationException($"Service is not registered: {typeof(T).FullName}");
+}
+
+public interface IShrinkModUnload
+{
+    void OnUnload(ShrinkModContext context);
+}