Add backend projects with core models and tests, setup Godot frontend

backend/src/MyBiz.Core/City.cs

@@ -0,0 +1,47 @@
+namespace MyBiz.Core;
+
+/// <summary>
+/// Размер города
+/// </summary>
+public enum CitySize
+{
+    Small,      // Малый
+    Medium,     // Средний
+    Large       // Крупный
+}
+
+/// <summary>
+/// Город
+/// </summary>
+public class City
+{
+    public string Id { get; set; } = Guid.NewGuid().ToString();
+    public string Name { get; set; } = string.Empty;
+    public string Country { get; set; } = string.Empty;
+    public CitySize Size { get; set; }
+    
+    /// <summary>
+    /// Население
+    /// </summary>
+    public int Population { get; set; }
+    
+    /// <summary>
+    /// Доступные здания
+    /// </summary>
+    public List<Building> Buildings { get; set; } = new();
+    
+    /// <summary>
+    /// Рынок города (спрос на продукты)
+    /// </summary>
+    public Dictionary<ProductType, int> MarketDemand { get; set; } = new();
+    
+    /// <summary>
+    /// Предложение на рынке
+    /// </summary>
+    public Dictionary<ProductType, int> MarketSupply { get; set; } = new();
+    
+    /// <summary>
+    /// Текущие цены
+    /// </summary>
+    public Dictionary<ProductType, decimal> Prices { get; set; } = new();
+}