KNI spike: engine core + Friflo render via WebGL in the browser

spikes/KniWeb (outside LittleSim.sln): a kni-blazor-gl template project
(KNI 4.2.9001, net8.0) referencing MrGameEng.Core directly. A mini-host
in the GameHost mold drives EngineContext/GameClock/Scene phases over
KNI's Game; the scene moves 300 Friflo entities in the update phase and
draws them with SpriteBatch (WebGL). Verified in a real browser: sprites
render and animate, browser console is clean.

Decision (docs/web-client.md): path A — KNI — is the primary route for
the web client; the core runs in Blazor WASM unchanged thanks to the
Core/Host split. Known follow-ups: per-platform compilation of the
graphics libraries against nkast.* packages, shader compatibility for
Renderer2D, HTTP-served content instead of the filesystem.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

spikes/KniWeb/Program.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Components.Web;
+using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace KniWebSpike
+{
+    internal class Program
+    {
+        private static async Task Main(string[] args)
+        {
+            var builder = WebAssemblyHostBuilder.CreateDefault(args);
+            builder.RootComponents.Add<App>("#app");
+            builder.RootComponents.Add<HeadOutlet>("head::after");
+            builder.Services.AddScoped(sp => new HttpClient()
+            {
+                BaseAddress = new Uri(builder.HostEnvironment.BaseAddress)
+            });
+            await builder.Build().RunAsync();
+        }
+    }
+}