Add shared frontend primitive components

src/RolemasterDb.App/Components/Primitives/SurfaceDrawer.razor

@@ -0,0 +1,77 @@
+@if (IsOpen)
+{
+    <button
+        type="button"
+        class="surface-drawer-backdrop"
+        aria-label="@CloseLabel"
+        @onclick="HandleCloseAsync"></button>
+
+    <aside class="@BuildCssClass()" aria-label="@AriaLabel">
+        @if (!string.IsNullOrWhiteSpace(Title) || HeaderContent is not null || OnClose.HasDelegate)
+        {
+            <header class="surface-drawer-header">
+                <div>
+                    @if (!string.IsNullOrWhiteSpace(Title))
+                    {
+                        <strong class="surface-drawer-title">@Title</strong>
+                    }
+                </div>
+
+                <div class="surface-drawer-header-actions">
+                    @HeaderContent
+                    @if (OnClose.HasDelegate)
+                    {
+                        <button type="button" class="btn btn-link" @onclick="HandleCloseAsync">Close</button>
+                    }
+                </div>
+            </header>
+        }
+
+        <div class="surface-drawer-body">
+            @ChildContent
+        </div>
+    </aside>
+}
+
+@code {
+    [Parameter]
+    public bool IsOpen { get; set; }
+
+    [Parameter]
+    public string Placement { get; set; } = "end";
+
+    [Parameter]
+    public string AriaLabel { get; set; } = "Drawer";
+
+    [Parameter]
+    public string CloseLabel { get; set; } = "Close panel";
+
+    [Parameter]
+    public string? Title { get; set; }
+
+    [Parameter]
+    public RenderFragment? HeaderContent { get; set; }
+
+    [Parameter]
+    public RenderFragment? ChildContent { get; set; }
+
+    [Parameter]
+    public EventCallback OnClose { get; set; }
+
+    [Parameter]
+    public string? CssClass { get; set; }
+
+    private string BuildCssClass()
+    {
+        var classes = new List<string> { "surface-drawer", $"is-{Placement.Trim().ToLowerInvariant()}" };
+        if (!string.IsNullOrWhiteSpace(CssClass))
+        {
+            classes.Add(CssClass);
+        }
+
+        return string.Join(' ', classes);
+    }
+
+    private Task HandleCloseAsync() =>
+        OnClose.InvokeAsync();
+}