Push API changes

* Fix item repair cost formula
* Add "RequestUpdateAvailableFreeLoadout" function (WIP)
* Fix item sell formula
* Fix item stack split on sell
* Fix contract progression counting for objectives other than owned items
* Refactor balance into a proper struct
* Separate and update Season 2 and Season 3 data

src/Prospect.Server.Api/Models/Data/DatabaseModels.cs

@@ -0,0 +1,15 @@
+using System.Text.Json.Serialization;
+
+namespace Prospect.Server.Api.Models.Data;
+
+public class PlayerBalance
+{
+    [JsonPropertyName("AU")]
+    public int HardCurrency { get; set; }
+
+    [JsonPropertyName("SC")]
+    public int SoftCurrency { get; set; }
+
+    [JsonPropertyName("IN")]
+    public int InsuranceTokens { get; set; }
+}