feat(infrastructure): ProductRepository + ProductQueryRepository, DI swap activates guard (PRD-002)

src/api/SIGCM2.Infrastructure/DependencyInjection.cs

@@ -40,6 +40,9 @@ public static class DependencyInjection
         services.AddScoped<IIngresosBrutosRepository, IngresosBrutosRepository>();
         services.AddScoped<IRubroRepository, RubroRepository>();
         services.AddScoped<IProductTypeRepository, ProductTypeRepository>();
+        services.AddScoped<IProductRepository, ProductRepository>();
+        // PRD-002: replaces NullProductQueryRepository from Application DI
+        services.AddScoped<IProductQueryRepository, ProductQueryRepository>();
 
         // JWT Options — bound lazily via IOptions so tests can override via ConfigureWebHost
         services.Configure<JwtOptions>(configuration.GetSection("Jwt"));