feat(render): Vulkan campaign V11 step 2 — delete the OpenGL backend

Vulkan is the sole, user-signed-off backend (V10 landed) and step 1
already removed ImGui/Studio/DevTools. This step deletes the GL
rendering backend itself: every Gpu/Gl/** implementation, the Wb
ManagedGL*/GLHelpers/GLSLShader/GLStateScope/RenderStateCache/
BindlessSupport family, Shader/ShaderProgramConstruction/SamplerCache,
RenderBootstrap, and RenderFrameGlStateController.

GameWindow.cs's Run()/CreateGraphics()/CreateBackbufferReader()/
OnLoad() collapse to their Vulkan-only arm; GameWindowGraphics loses
its OpenGlGameWindowGraphics subclass. RuntimeOptions.RenderBackend and
RenderBackendKind (incl. the Gl member of GpuBackendKind) are gone —
there is nothing left to select between. The five world-draw dual-arm
renderers (WbDrawDispatcher, EnvCellRenderer, TerrainModernRenderer,
ParticleRenderer, SkyRenderer) and the composition roots
(WorldRenderComposition, HostInputCameraComposition,
LivePresentationComposition, FrameRootComposition) collapse to their
RHI-only arm. GL-only diagnostic properties with a live external reader
(DynamicBufferCount and friends) simplify to a documented `=> 0`/no-op
rather than disappearing, since the reader is out of this commit's
scope.

A few GL-flavored mechanisms turned out to be backend-neutral once
isolated: GlConstructionCleanupLedger is renamed
ResourceConstructionCleanupLedger (exception-chain walking has nothing
to do with GL), and GlfwNativePlatformProbe moved out of the otherwise
GL-only GraphicalCapabilityRecord.cs into
GraphicalWindowBackendSelection.cs before the rest of that file was
deleted.

Test files with no surviving subject are deleted outright
(GraphicalCapabilityRequirementsTests, ShaderProgramConstructionTests,
PortalDepthShaderParityTests, TextureCacheBindlessTests,
TextRendererFailureSafetyTests, ClipFrameUploadTests, every
Gpu/Gl/*Tests, GlTextureOwnershipTests, RenderFrameGlStateControllerTests);
others get their dead GL-only members trimmed while their live
assertions stay (ClipFrameLayoutTests' MeshClipSsboBinding check now
reads GpuBindingModel.StorageClipRegions, the same binding index under
its new backend-neutral name; GpuResourceRetirementTransactionTests
drops its OpenGLGraphicsDevice-subclassing test double and the two GL
queue tests it existed for). EnvCellRendererTests' construction helper
now builds a real ObjectMeshManager via VulkanMeshPipelineDevice
instead of passing null through a null-forgiving operator, since the
RHI constructor never tolerated a null mesh manager and the old GL
constructor (which did) is gone.

Deferred to the next two steps, deliberately not touched here: the
Silk.NET.OpenGL/.Extensions.ARB package references, IMeshPipelineDevice.Gl
(WbMeshAdapter's GL? threading stays in place), Chorizite.Core's stale
csproj comment (the package itself is still load-bearing —
TextureFormat and friends are used well beyond the deleted
ManagedGLUniformBuffer), and the CI/gate scripts.

Build: `dotnet build AcDream.slnx -c Release` — 0 warnings, 0 errors.
Tests: full-solution `dotnet test` green across every project
(App.Tests 3937/3940 + 3 skips, Core.Tests 3296/3298 + 2 skips, all
others 100%); the 2 App.Tests names that flake under full-suite
parallel execution (#250-family, documented pre-existing) pass in
isolation.

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

src/AcDream.App/Composition/VulkanHostInputCameraCompositionFactory.cs

@@ -8,28 +8,22 @@ using Silk.NET.Input;
 namespace AcDream.App.Composition;
 
 /// <summary>
-/// Campaign V slice V6h: the Vulkan arm of the host phase.
-///
-/// <para>This is the whole of the backend fork at composition Phase 1. Only the
-/// four graphics members differ from
-/// <see cref="RetailHostInputCameraCompositionFactory"/>; input, camera and
-/// pointer construction are platform concerns, not graphics ones, so they
-/// delegate rather than duplicate. Adding a fifth backend would add one more
-/// class of this shape and touch nothing else in the composition pipeline —
-/// which is the property §5.5.9 asked this slice to establish.</para>
+/// Campaign V slice V6h: the Vulkan arm of the host phase — now the only arm,
+/// the raw-GL <c>RetailHostInputCameraCompositionFactory</c> it used to fork
+/// from having been deleted at slice V11. Input, camera and pointer
+/// construction are inlined directly rather than delegated, since there is no
+/// longer a second implementation to share them with.
 ///
 /// <para><b>What is absent, and why.</b> There is no GL fence ring: the RHI
 /// device owns its own frames-in-flight through a timeline semaphore, so
 /// retirement and slot indexing come from the device instead. There is no
-/// <see cref="WorldRenderDiagnostics"/>: it is a raw-GL state tripwire, and
+/// <see cref="WorldRenderDiagnostics"/>: it was a raw-GL state tripwire, and
 /// Vulkan has no global state for it to watch. Both nulls are read by the
 /// phases that would otherwise consume them.</para>
 /// </summary>
 internal sealed class VulkanHostInputCameraCompositionFactory
     : IHostInputCameraCompositionFactory
 {
-    private readonly RetailHostInputCameraCompositionFactory _platform = new();
-
     public IFramebufferViewportTarget CreateViewportTarget(
         GameWindowGraphics graphics) =>
         // The viewport is a pipeline dynamic state on Vulkan, set per pass by
@@ -64,29 +58,29 @@ internal sealed class VulkanHostInputCameraCompositionFactory
     public SilkKeyboardSource CreateKeyboardSource(
         IKeyboard keyboard,
         HostQuiescenceGate quiescence) =>
-        _platform.CreateKeyboardSource(keyboard, quiescence);
+        SilkKeyboardSource.CreateDetached(keyboard, quiescence);
 
     public SilkMouseSource CreateMouseSource(
         IMouse mouse,
         IInputCaptureSource capture,
         IKeyboardSource? keyboard,
         HostQuiescenceGate quiescence) =>
-        _platform.CreateMouseSource(mouse, capture, keyboard, quiescence);
+        SilkMouseSource.CreateDetached(mouse, capture, keyboard, quiescence);
 
     public IMouseLookCursor CreateMouseLookCursor(IMouse mouse) =>
-        _platform.CreateMouseLookCursor(mouse);
+        new SilkMouseLookCursor(mouse);
 
     public InputDispatcher CreateInputDispatcher(
         IKeyboardSource keyboard,
         IMouseSource mouse,
         KeyBindings bindings) =>
-        _platform.CreateInputDispatcher(keyboard, mouse, bindings);
+        InputDispatcher.CreateDetached(keyboard, mouse, bindings);
 
     public CameraController CreateCameraController() =>
-        _platform.CreateCameraController();
+        new(new OrbitCamera(), new FlyCamera());
 
     public IFramebufferCameraTarget CreateCameraTarget(CameraController camera) =>
-        _platform.CreateCameraTarget(camera);
+        new CameraFramebufferTarget(camera);
 
     public CameraPointerInputController CreateCameraPointerInput(
         IReadOnlyList<IMouse> mice,
@@ -97,7 +91,7 @@ internal sealed class VulkanHostInputCameraCompositionFactory
         ChaseCameraInputState chase,
         IMouseSource mouse,
         PointerPositionState pointer) =>
-        _platform.CreateCameraPointerInput(
+        CameraPointerInputController.Create(
             mice,
             quiescence,
             capture,
@@ -105,14 +99,15 @@ internal sealed class VulkanHostInputCameraCompositionFactory
             camera,
             chase,
             mouse,
-            pointer);
+            pointer,
+            new EnvironmentInputMonotonicClock());
 
     private static VulkanGraphicsContext RequireContext(
         GameWindowGraphics graphics) =>
         graphics.Vulkan
         ?? throw new InvalidOperationException(
-            "The Vulkan host factory was composed against the " +
-            $"{graphics.Backend} backend.");
+            "The Vulkan host factory was composed against a backend with no " +
+            "Vulkan context.");
 
     /// <summary>
     /// Vulkan sets the viewport per pass from the pass extent, so there is no