feat(achievements): /achievement/receive_reward — RewardGrantService + level advance + cap

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

SVSim.EmulatedEntrypoint/Models/Dtos/Achievement/AchievementReceiveRewardRequest.cs

@@ -0,0 +1,17 @@
+using System.Text.Json.Serialization;
+using MessagePack;
+using SVSim.EmulatedEntrypoint.Models.Dtos.Requests;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Achievement;
+
+[MessagePackObject]
+public class AchievementReceiveRewardRequest : BaseRequest
+{
+    [Key("achievement_type")]
+    [JsonPropertyName("achievement_type")]
+    public int AchievementType { get; set; }
+
+    [Key("level")]
+    [JsonPropertyName("level")]
+    public int Level { get; set; }
+}