squash a bunch of commits

Shogi.UI/Pages/Home/PageHeader.razor

@@ -0,0 +1,31 @@
+@inject AccountState Account
+@inject AccountManager AccountManager
+
+<div class="pageHeader">
+    <h1>Shogi</h1>
+    @if (user != null)
+    {
+        <div class="user">
+            <div>@user.DisplayName</div>
+            <button type="button" class="logout" @onclick="AccountManager.LogoutAsync">Logout</button>
+        </div>
+    }
+    @*<LoginDisplay />*@
+</div>
+
+@code {
+    private User? user;
+
+    protected override void OnInitialized()
+    {
+        Account.LoginChangedEvent += OnLoginChange;
+    }
+
+    private void OnLoginChange(object? sender, LoginEventArgs args)
+    {
+        if (args == null)
+            throw new ArgumentException(nameof(args));
+        user = args.User;
+        StateHasChanged();
+    }
+}