Slice 2 (WIP): class carrier (GoInGameRequest.ClassId) + Warrior cone archetype

The per-player class travels on GoInGameRequest.ClassId (client reads a ClassSelection
singleton); GoInGameServerSystem seeds the class at spawn via ClassTraits (AbilityRef +
permanent trait StatModifiers on a reserved ClassSourceId; CharacterStatsRef stays Default
so the DRG-asymmetry deltas ride the replicated OwnerSendType.All buffer). AbilityFireSystem
gains the aim-directed Cone archetype: cooldown predicted both worlds, server-only cone
damage to living enemies (same-tick, SourceTick-stamped, like the melee cleave). 345/345.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Assets/_Project/Scripts/Client/Connection/GoInGameClientSystem.cs

@@ -36,8 +36,9 @@ namespace ProjectM.Client
             {
                 ecb.AddComponent<NetworkStreamInGame>(connection);
 
+                byte classId = SystemAPI.HasSingleton<ClassSelection>() ? SystemAPI.GetSingleton<ClassSelection>().ClassId : (byte)0;
                 var request = ecb.CreateEntity();
-                ecb.AddComponent<GoInGameRequest>(request);
+                ecb.AddComponent(request, new GoInGameRequest { ClassId = classId }); // Slice 2: carry the chosen class
                 ecb.AddComponent(request, new SendRpcCommandRequest { TargetConnection = connection });
             }