feat(profile): ProfileController + DTOs + integration tests

Add /profile/index endpoint that returns user_rank_match_total_win (stubbed 0)
and user_class_list built from viewer Classes + owned LeaderSkins. Six NUnit
integration tests cover zero wins, all classes present, level/exp/default skin,
leader_skin_id_list population, is_random_leader_skin round-trip, and 401 on
unauthenticated access.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

SVSim.EmulatedEntrypoint/Models/Dtos/Profile/ProfileIndexResponse.cs

@@ -0,0 +1,17 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Profile;
+
+[MessagePackObject]
+public sealed class ProfileIndexResponse
+{
+    [JsonPropertyName("user_rank_match_total_win")]
+    [Key("user_rank_match_total_win")]
+    public int UserRankMatchTotalWin { get; set; }
+
+    [JsonPropertyName("user_class_list")]
+    [Key("user_class_list")]
+    public List<UserClass> UserClassList { get; set; } = new();
+}