feat(render): implement Campaign AR and terrain fidelity

tests/AcDream.Core.Tests.Fixtures.HelloPlugin/HelloPlugin.cs

@@ -1,8 +1,9 @@
 using AcDream.Plugin.Abstractions;
+using AcDream.Plugin.Abstractions.Rendering;
 
 namespace AcDream.Core.Tests.Fixtures.HelloPlugin;
 
-public sealed class HelloPlugin : IAcDreamPlugin
+public sealed class HelloPlugin : IAcDreamPlugin, IRenderPackPlugin, IRenderPackAssets
 {
     public int InitializeCount { get; private set; }
     public int EnableCount { get; private set; }
@@ -17,4 +18,39 @@ public sealed class HelloPlugin : IAcDreamPlugin
 
     public void Enable() => EnableCount++;
     public void Disable() => DisableCount++;
+
+    public void Register(IRenderPackRegistry registry)
+    {
+        ArgumentNullException.ThrowIfNull(registry);
+        _ = registry.Register(
+            new RenderPackDescriptor(
+                Id: "acdream.test.noop-pack",
+                DisplayName: "Test no-op pack",
+                PackVersion: new Version(1, 0, 0),
+                PackApiVersion: RenderPackApi.Current,
+                HighestTier: RenderPackTier.Tier1,
+                RequiredCapabilities: [],
+                OptionalCapabilities: [],
+                Resources: [],
+                Passes: [],
+                SceneReplays: [],
+                PipelineVariants: [],
+                QualityPresets: [],
+                Settings: [],
+                AtmospherePolicy: null)
+            {
+                FeatureSummary = "Test-only no-op render-pack fixture.",
+            },
+            this);
+        string? directory = Path.GetDirectoryName(typeof(HelloPlugin).Assembly.Location);
+        if (directory is not null
+            && File.Exists(Path.Combine(directory, "throw-after-render-register")))
+        {
+            throw new InvalidOperationException(
+                "fixture render-pack registration failed after publishing a descriptor");
+        }
+    }
+
+    public Stream OpenRead(string assetKey) =>
+        new MemoryStream([], writable: false);
 }