Refactor GameRepository and GameManager architecture, introduce Player model, and update dependency registration in Program.cs.

API/Program.cs

@@ -1,4 +1,5 @@
 using API.Controllers;
+using API.Repository.GameRepo;
 using API.Services.GameManager;
 
 var builder = WebApplication.CreateBuilder(args);
@@ -11,6 +12,7 @@ builder.Services.AddOpenApi();
 builder.Services.AddSwaggerGen();
 
 builder.Services.AddSingleton<IGameManager, GameManager>();
+builder.Services.AddSingleton<IGameRepository, GameRepository>();
 
 var app = builder.Build();