feat(TFARegController): Initialisiert den MVC-Controller und den View zur Bearbeitung der TFA-Registrierung.

EnvelopeGenerator.Web/Controllers/TFARegController.cs

@@ -0,0 +1,14 @@
+using Microsoft.AspNetCore.Mvc;
+
+namespace EnvelopeGenerator.Web.Controllers;
+
+//TODO: Add authorization as well as limiting the link duration (intermediate token with different role)
+[Route("tfa")]
+public class TFARegController : Controller
+{
+    [HttpGet("{key}")]
+    public IActionResult Reg(string key)
+    {
+        return View();
+    }
+}

EnvelopeGenerator.Web/Views/TFAReg/Reg.cshtml

@@ -0,0 +1,14 @@
+@{
+    ViewData["Title"] = "Reg";
+}
+<div class="page container p-5">
+    <header class="text-center">
+        <div class="icon expired">
+            <svg width="72" height="72" viewBox="0 0 48 48" version="1" xmlns="http://www.w3.org/2000/svg" enable-background="new 0 0 48 48"></svg>
+        </div>
+        <h1>Title</h1>
+    </header>
+    <section class="text-center">
+        <p>Summary</p>
+    </section>
+</div>