refactor(UXAssist): harden ModFeatureRegistry

UXAssist/Common/ModFeatures/ModFeatureAttribute.cs

@@ -2,12 +2,27 @@ using System;
 
 namespace UXAssist.Common.ModFeatures;
 
+/// <summary>
+/// Marks a static class as a mod feature so that <see cref="ModFeatureRegistry"/> can discover it.
+/// Lifecycle methods (<c>Init</c>, <c>Start</c>, <c>Uninit</c>, <c>OnInputUpdate</c>, <c>OnUpdate</c>) are optional.
+/// </summary>
 [AttributeUsage(AttributeTargets.Class, Inherited = false)]
 public sealed class ModFeatureAttribute : Attribute
 {
+    /// <summary>
+    /// Optional display name of the feature.
+    /// </summary>
     public string Name { get; }
+
+    /// <summary>
+    /// Execution order among discovered static features. Lower values run first.
+    /// </summary>
     public int Order { get; set; }
 
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ModFeatureAttribute"/> class.
+    /// </summary>
+    /// <param name="name">Optional display name of the feature.</param>
     public ModFeatureAttribute(string name = null)
     {
         Name = name;