Refactor code structure for improved readability and maintainability

dotnet/src/TwitchArchive.Web/Pages/Login.razor

@@ -0,0 +1,20 @@
+@page "/login"
+@attribute [AllowAnonymous]
+@using Microsoft.AspNetCore.Components
+
+<h3>Login</h3>
+
+@if (error)
+{
+    <div class="alert">Invalid password</div>
+}
+
+<form method="post" action="/auth/login">
+    <input type="password" name="password" placeholder="Password" />
+    <button type="submit">Login</button>
+</form>
+
+@code {
+    [Parameter]
+    public bool error { get; set; }
+}