add xmldoc comments

web/backend/API/API.Core/Controllers/ProtectedController.cs

@@ -5,11 +5,22 @@ using Microsoft.AspNetCore.Mvc;
 
 namespace API.Core.Controllers;
 
+/// <summary>
+/// Sample controller demonstrating an endpoint that requires JWT authentication.
+/// </summary>
 [ApiController]
 [Route("api/[controller]")]
 [Authorize(AuthenticationSchemes = "JWT")]
 public class ProtectedController : ControllerBase
 {
+    /// <summary>
+    /// Returns the authenticated caller's user ID and username, extracted from the JWT claims.
+    /// </summary>
+    /// <returns>
+    /// A <c>200 OK</c> result wrapping a <see cref="ResponseBody{T}"/> whose payload contains the
+    /// caller's <c>userId</c> (from <see cref="ClaimTypes.NameIdentifier"/>) and <c>username</c>
+    /// (from <see cref="ClaimTypes.Name"/>), either of which may be <c>null</c> if not present in the token.
+    /// </returns>
     [HttpGet]
     public ActionResult<ResponseBody<object>> Get()
     {