Switch AltersGruppe ID to ULID and add config

Changed AltersGruppe model ID from int to string and now generates ULID automatically. Added AltersGruppeConfiguration for EF Core mapping. Updated ApplicationDbContext to apply configurations from assembly. Removed obsolete migration files and database artifacts. Added Ulid package dependency.

API/Migrations/ApplicationDbContextModelSnapshot.cs

@@ -1,42 +0,0 @@
-// <auto-generated />
-using API.Database;
-using Microsoft.EntityFrameworkCore;
-using Microsoft.EntityFrameworkCore.Infrastructure;
-using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
-
-#nullable disable
-
-namespace API.Migrations
-{
-    [DbContext(typeof(ApplicationDbContext))]
-    partial class ApplicationDbContextModelSnapshot : ModelSnapshot
-    {
-        protected override void BuildModel(ModelBuilder modelBuilder)
-        {
-#pragma warning disable 612, 618
-            modelBuilder.HasAnnotation("ProductVersion", "9.0.11");
-
-            modelBuilder.Entity("API.Models.Internal.Altersgruppen.AltersGruppe", b =>
-                {
-                    b.Property<int>("Id")
-                        .ValueGeneratedOnAdd()
-                        .HasColumnType("INTEGER");
-
-                    b.Property<int>("EndingAge")
-                        .HasColumnType("INTEGER");
-
-                    b.Property<string>("Name")
-                        .IsRequired()
-                        .HasColumnType("TEXT");
-
-                    b.Property<int>("StartingAge")
-                        .HasColumnType("INTEGER");
-
-                    b.HasKey("Id");
-
-                    b.ToTable("Altersgruppen");
-                });
-#pragma warning restore 612, 618
-        }
-    }
-}