feat: initial datamodel + ef connection and migrations

Initial version of the data model
Includes EF initialization and migrations
EF migrations are applied on application start

TournamentOrganizer/Models/Team.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace TournamentOrganizer.Models;
+
+public class Team
+{
+    [Key]
+    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+    public int Id { get; set; }
+    public string Name { get; set; } = "Example Team";
+
+    public required List<Player> Players { get; set; }
+    public required List<TeamParticipant> Matches { get; set; }
+
+}