Align user/project collection and item usage with rest of codebase

src/IModifiableProject.cs

@@ -3,7 +3,7 @@
 /// <summary>
 /// Represents a project that can be modified.
 /// </summary>
-public interface IModifiableProject : IReadOnlyProject, IModifiableEntity, IModifiableImagesCollection, IModifiableUserRoleCollection, IModifiableAccentColor
+public interface IModifiableProject : IReadOnlyProject, IModifiableEntity, IModifiableImagesCollection, IModifiableUserRoleCollection, IModifiableAccentColor, IModifiableFeaturesCollection
 {
     /// <summary>
     /// Updates the publisher for this project.

src/IModifiableProjectRole.cs

@@ -0,0 +1,8 @@
+namespace WinAppCommunity.Sdk;
+
+/// <summary>
+/// Represents a project with a corresponding role that can be modified.
+/// </summary>
+public interface IModifiableProjectRole : IReadOnlyProjectRole, IModifiableProject
+{
+}

src/IReadOnlyProject.cs

@@ -10,7 +10,7 @@ public interface IReadOnlyProject : IReadOnlyProject<IReadOnlyProjectCollection>
 /// <summary>
 /// Represents a project.
 /// </summary>
-public interface IReadOnlyProject<TDependencyCollection> : IReadOnlyEntity, IReadOnlyImagesCollection, IReadOnlyUserRoleCollection, IReadOnlyAccentColor
+public interface IReadOnlyProject<out TDependencyCollection> : IReadOnlyEntity, IReadOnlyImagesCollection, IReadOnlyUserRoleCollection, IReadOnlyAccentColor, IReadOnlyFeaturesCollection
     where TDependencyCollection : IReadOnlyProjectCollection
 {
     /// <summary>

src/IReadOnlyUserCollection.cs

@@ -13,7 +13,7 @@ public interface IReadOnlyUserCollection : IReadOnlyUserCollection<IReadOnlyUser
 /// Represents a collection of users with a corresponding role that can be modified.
 /// </summary>
 /// <typeparam name="TUser">The type of user in this collection.</typeparam>
-public interface IReadOnlyUserCollection<TUser>
+public interface IReadOnlyUserCollection<out TUser>
     where TUser : IReadOnlyUser
 {
     /// <summary>