Add minimal auth

Pages/Login.cshtml

@@ -0,0 +1,5 @@
+@page
+
+<p>
+    :D (login)
+</p>

Pages/NewDefinition.cshtml.cs

@@ -5,9 +5,15 @@ namespace JergueroCS.Pages
 {
     public class NewDefinitionModel : PageModel
     {
-        public void OnGet()
+        public IActionResult OnGet()
         {
+            if (User.Identity?.IsAuthenticated != true)
+            {
+                return RedirectToPage("/Login");
+            }
+
             System.Console.WriteLine(":D");
+            return Page();
         }
     }
 }

Program.cs

@@ -1,7 +1,16 @@
+using Microsoft.AspNetCore.Authentication.Cookies;
+
 var builder = WebApplication.CreateBuilder(args);
 
 // Add services to the container.
 builder.Services.AddRazorPages();
+builder.Services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
+    .AddCookie(options =>
+    {
+        options.ExpireTimeSpan = TimeSpan.FromMinutes(20);
+        options.SlidingExpiration = true;
+        options.AccessDeniedPath = "/Forbidden/";
+    });
 
 var app = builder.Build();
 
@@ -18,6 +27,11 @@ app.UseStaticFiles();
 
 app.UseRouting();
 
+app.UseCookiePolicy(new CookiePolicyOptions
+{
+    MinimumSameSitePolicy = SameSiteMode.Strict,
+});
+app.UseAuthentication();
 app.UseAuthorization();
 
 app.MapRazorPages();