feat: Implement MintPlayer.AspNetCore.Endpoints library (#27)

* Add MintPlayer.AspNetCore.Endpoints library (Phase 1 + 2)

Three-package implementation for class-per-endpoint mapping:

- Abstractions: interfaces (IEndpointBase, IEndpoint, IEndpoint<T>,
  IEndpoint<T,R>), convenience interfaces (IGet/Post/Put/Delete/Patch),
  IEndpointGroup + IMemberOf<T> for route groups, attributes, descriptor

- Runtime: abstract base class hierarchy (EndpointBase<T> -> BodyEndpoint<T>
  with MVC input formatter content negotiation + JSON fallback,
  NonBodyEndpoint<T> with forced explicit binding), concrete HTTP method
  classes, MapEndpoint<T> manual registration extension

- Generator: IIncrementalGenerator that discovers endpoints, generates
  partial class base declarations (Task A) and MapXxxEndpoints() extension
  method with factory caching, disposal, attribute transfer, group support,
  and .Produces<TResponse>() for OpenAPI (Task B)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Add test app and rewrite generator using MintPlayer.SourceGenerators.Tools

- Rewrote generator to use IncrementalGenerator base class and Producer
  pattern with IndentedTextWriter/OpenBlock from MintPlayer.SourceGenerators.Tools
- Fixed ObjectFactory<T> type (was incorrectly using Func<...>)
- Removed Emitter.cs, replaced with EndpointGenerator.Producer.cs
- Added TestApp exercising all endpoint types:
  - Raw GET (HealthCheck)
  - POST with typed request+response in group (CreateUser)
  - GET with explicit binding in group (GetUser)
  - PUT with body parsing in group (UpdateUser)
  - DELETE with explicit binding in group (DeleteUser)
  - Raw GET in group (ListUsers)
  - Multi-method endpoint (PreflightEndpoint)
  - Route group with tags (UsersApi)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* Bundle source generator in runtime package and add README

- Fix BodyEndpoint content negotiation to guard on IModelMetadataProvider
- Apply [assembly: EndpointsMethodName] in test app
- Pack generator + dependencies into analyzers/dotnet/cs of runtime package
- Add comprehensive README.md included in NuGet package

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* launchsettings

* Support nested endpoint groups at any depth

- Add GroupInfo model and second syntax provider for group-to-parent discovery
- Groups can implement IMemberOf<TParentGroup> for nesting
- Generator builds group tree and emits nested MapGroup calls
- Add ApiGroup, ProductsApi, and ListProducts to test app
- Update README with nested groups documentation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: PieterjanDeClippel

Endpoints/MintPlayer.AspNetCore.Endpoints.Abstractions/EndpointDescriptor.cs

@@ -0,0 +1,3 @@
+namespace MintPlayer.AspNetCore.Endpoints;
+
+public record EndpointDescriptor(string Name, string Path, IEnumerable<string> Methods, Type HandlerType);

Endpoints/MintPlayer.AspNetCore.Endpoints.Abstractions/EndpointNameAttribute.cs

@@ -0,0 +1,7 @@
+namespace MintPlayer.AspNetCore.Endpoints;
+
+[AttributeUsage(AttributeTargets.Class)]
+public class EndpointNameAttribute(string name) : Attribute
+{
+    public string Name { get; } = name;
+}

Endpoints/MintPlayer.AspNetCore.Endpoints.Abstractions/EndpointsMethodNameAttribute.cs

@@ -0,0 +1,12 @@
+namespace MintPlayer.AspNetCore.Endpoints;
+
+/// <summary>
+/// Overrides the name of the generated MapEndpoints extension method for this assembly.
+/// Without this attribute, the method name is derived from the assembly name
+/// (e.g., assembly "MyApp.Api" -> "MapMyAppApiEndpoints").
+/// </summary>
+[AttributeUsage(AttributeTargets.Assembly, AllowMultiple = false)]
+public class EndpointsMethodNameAttribute(string methodName) : Attribute
+{
+    public string MethodName { get; } = methodName;
+}

Endpoints/MintPlayer.AspNetCore.Endpoints.Abstractions/IDeleteEndpoint.cs

@@ -0,0 +1,16 @@
+namespace MintPlayer.AspNetCore.Endpoints;
+
+public interface IDeleteEndpoint : IEndpoint
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["DELETE"];
+}
+
+public interface IDeleteEndpoint<TRequest> : IEndpoint<TRequest>
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["DELETE"];
+}
+
+public interface IDeleteEndpoint<TRequest, TResponse> : IEndpoint<TRequest, TResponse>
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["DELETE"];
+}

Endpoints/MintPlayer.AspNetCore.Endpoints.Abstractions/IEndpoint.cs

@@ -0,0 +1,31 @@
+namespace MintPlayer.AspNetCore.Endpoints;
+
+/// <summary>
+/// Level 1: Raw endpoint — full control over HttpContext.
+/// </summary>
+public interface IEndpoint : IEndpointBase
+{
+    Task<IResult> HandleAsync(HttpContext httpContext);
+}
+
+/// <summary>
+/// Level 2: Typed request — automatic request binding via the abstract base class.
+/// </summary>
+public interface IEndpoint<TRequest> : IEndpoint
+{
+    Task<IResult> HandleAsync(TRequest request, CancellationToken cancellationToken);
+}
+
+/// <summary>
+/// Level 3: Typed request and response — full type information for OpenAPI/Swagger.
+/// TResponse is used by the source generator to emit .Produces&lt;TResponse&gt;(statusCode).
+/// </summary>
+public interface IEndpoint<TRequest, TResponse> : IEndpoint<TRequest>
+{
+    /// <summary>
+    /// The HTTP status code for successful responses.
+    /// Used by the source generator for .Produces&lt;TResponse&gt;(statusCode).
+    /// Default: 200 (OK).
+    /// </summary>
+    static virtual int SuccessStatusCode => 200;
+}

Endpoints/MintPlayer.AspNetCore.Endpoints.Abstractions/IEndpointBase.cs

@@ -0,0 +1,22 @@
+namespace MintPlayer.AspNetCore.Endpoints;
+
+/// <summary>
+/// Base contract for all endpoints. Provides route metadata as static abstract members.
+/// </summary>
+public interface IEndpointBase
+{
+    /// <summary>The route pattern (e.g., "/api/users/{id}").</summary>
+    static abstract string Path { get; }
+
+    /// <summary>
+    /// The HTTP methods this endpoint handles (e.g., ["GET"], ["POST"], ["GET", "HEAD"]).
+    /// Convenience interfaces (IGetEndpoint, IPostEndpoint, etc.) provide this automatically.
+    /// </summary>
+    static abstract IEnumerable<string> Methods { get; }
+
+    /// <summary>
+    /// Optional hook to configure the route handler (auth, caching, OpenAPI metadata, etc.).
+    /// Default implementation is a no-op.
+    /// </summary>
+    static virtual void Configure(RouteHandlerBuilder builder) { }
+}

Endpoints/MintPlayer.AspNetCore.Endpoints.Abstractions/IEndpointGroup.cs

@@ -0,0 +1,23 @@
+namespace MintPlayer.AspNetCore.Endpoints;
+
+/// <summary>
+/// Defines a route group with a shared prefix and optional group-wide configuration.
+/// Endpoints join a group by implementing IMemberOf&lt;TGroup&gt;.
+/// </summary>
+public interface IEndpointGroup
+{
+    /// <summary>The route prefix for all endpoints in this group (e.g., "/api/users").</summary>
+    static abstract string Prefix { get; }
+
+    /// <summary>
+    /// Optional hook to configure the route group (auth, rate limiting, CORS, tags, etc.).
+    /// Default implementation is a no-op.
+    /// </summary>
+    static virtual void Configure(RouteGroupBuilder group) { }
+}
+
+/// <summary>
+/// Marker interface that associates an endpoint with an endpoint group.
+/// The endpoint's Path becomes relative to the group's Prefix.
+/// </summary>
+public interface IMemberOf<TGroup> where TGroup : IEndpointGroup;

Endpoints/MintPlayer.AspNetCore.Endpoints.Abstractions/IGetEndpoint.cs

@@ -0,0 +1,16 @@
+namespace MintPlayer.AspNetCore.Endpoints;
+
+public interface IGetEndpoint : IEndpoint
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["GET"];
+}
+
+public interface IGetEndpoint<TRequest> : IEndpoint<TRequest>
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["GET"];
+}
+
+public interface IGetEndpoint<TRequest, TResponse> : IEndpoint<TRequest, TResponse>
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["GET"];
+}

Endpoints/MintPlayer.AspNetCore.Endpoints.Abstractions/IPatchEndpoint.cs

@@ -0,0 +1,16 @@
+namespace MintPlayer.AspNetCore.Endpoints;
+
+public interface IPatchEndpoint : IEndpoint
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["PATCH"];
+}
+
+public interface IPatchEndpoint<TRequest> : IEndpoint<TRequest>
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["PATCH"];
+}
+
+public interface IPatchEndpoint<TRequest, TResponse> : IEndpoint<TRequest, TResponse>
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["PATCH"];
+}

Endpoints/MintPlayer.AspNetCore.Endpoints.Abstractions/IPostEndpoint.cs

@@ -0,0 +1,16 @@
+namespace MintPlayer.AspNetCore.Endpoints;
+
+public interface IPostEndpoint : IEndpoint
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["POST"];
+}
+
+public interface IPostEndpoint<TRequest> : IEndpoint<TRequest>
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["POST"];
+}
+
+public interface IPostEndpoint<TRequest, TResponse> : IEndpoint<TRequest, TResponse>
+{
+    static IEnumerable<string> IEndpointBase.Methods => ["POST"];
+}