Added ASP.NET backend with SQLite

backend/MuiCharts.Contracts/Track/TrackResponse.cs

@@ -0,0 +1,14 @@
+using MuiCharts.Domain.Enums;
+
+namespace MuiCharts.Contracts.Track;
+
+/// <summary>
+/// Represents a response object for a track.
+/// </summary>
+public record TrackResponse(
+	int FirstId,
+	int SecondId,
+	int Distance,
+	Surface Surface,
+	MaxSpeed MaxSpeed
+);

backend/MuiCharts.Contracts/Track/UpsertTrackRequest.cs

@@ -0,0 +1,15 @@
+using System.ComponentModel.DataAnnotations;
+using MuiCharts.Domain.Enums;
+
+namespace MuiCharts.Contracts.Track;
+
+/// <summary>
+/// Represents a request to upsert a track.
+/// </summary>
+public record UpsertTrackRequest(
+	[Range(0, int.MaxValue)] int FirstId,
+	[Range(0, int.MaxValue)] int SecondId,
+	[Range(1, int.MaxValue)] int Distance,
+	Surface Surface,
+	MaxSpeed MaxSpeed
+);