Refactor code structure for improved readability and maintainability

apps/api/Program.cs

@@ -0,0 +1,75 @@
+using Microsoft.EntityFrameworkCore;
+
+var builder = WebApplication.CreateBuilder(args);
+
+builder.Services.AddDbContext<AppDbContext>(options =>
+    options.UseSqlite("Data Source=fitness.db"));
+
+builder.Services.AddEndpointsApiExplorer();
+builder.Services.AddOpenApiDocument();
+builder.Services.AddSwaggerGen();
+
+var app = builder.Build();
+
+if (app.Environment.IsDevelopment())
+{
+    app.UseOpenApi();
+    app.UseSwaggerUI();
+}
+
+app.UseHttpsRedirection();
+
+// ===================================================================
+// CRUD ENDPUNKTE (minimal, ohne Auth)
+// ===================================================================
+
+// CREATE
+app.MapPost("/api/workouts", async (Workout workout, AppDbContext db) =>
+{
+    workout.Id = Guid.NewGuid();
+    db.Workouts.Add(workout);
+    await db.SaveChangesAsync();
+    return Results.Created($"/api/workouts/{workout.Id}", workout);
+});
+
+// READ ALL
+app.MapGet("/api/workouts", async (AppDbContext db) =>
+    await db.Workouts.OrderByDescending(w => w.Date).ToListAsync());
+
+// READ BY ID
+app.MapGet("/api/workouts/{id:guid}", async (Guid id, AppDbContext db) =>
+    await db.Workouts.FindAsync(id) is Workout w ? Results.Ok(w) : Results.NotFound());
+
+// UPDATE
+app.MapPut("/api/workouts/{id:guid}", async (Guid id, Workout input, AppDbContext db) =>
+{
+    var workout = await db.Workouts.FindAsync(id);
+    if (workout is null) return Results.NotFound();
+
+    workout.Name = input.Name;
+    workout.Date = input.Date;
+    workout.DurationMinutes = input.DurationMinutes;
+    workout.Notes = input.Notes;
+    await db.SaveChangesAsync();
+    return Results.Ok(workout);
+});
+
+// DELETE
+app.MapDelete("/api/workouts/{id:guid}", async (Guid id, AppDbContext db) =>
+{
+    var workout = await db.Workouts.FindAsync(id);
+    if (workout is null) return Results.NotFound();
+
+    db.Workouts.Remove(workout);
+    await db.SaveChangesAsync();
+    return Results.NoContent();
+});
+
+app.MapGet("/", () => "🏋️ Fitness API läuft!");
+app.Run();
+
+public class AppDbContext : DbContext
+{
+    public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) { }
+    public DbSet<Workout> Workouts => Set<Workout>();
+}