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/Platform/GraphicalWindowBackendSelection.cs

@@ -187,3 +187,58 @@ internal static class GraphicalWindowBackendConfigurator
             DefaultPathResolver.BaseDirectoryResolver);
     }
 }
+
+/// <summary>
+/// Reads the GLFW platform actually selected at runtime (as opposed to the one
+/// requested — GLFW's <c>Automatic</c> hint can resolve to either X11 or
+/// Wayland). Moved here from the deleted (Campaign V slice V11) raw-GL
+/// <c>GraphicalCapabilityRecord.cs</c>: <see cref="VulkanGraphicsContext"/>
+/// depends on this for its own capability report, so it survived the GL arm
+/// that used to sit alongside it.
+/// </summary>
+internal static unsafe class GlfwNativePlatformProbe
+{
+    private const int GlfwWin32Platform = 0x00060001;
+    private const int GlfwWaylandPlatform = 0x00060003;
+    private const int GlfwX11Platform = 0x00060004;
+
+    internal static GraphicalDisplayProtocol GetActiveProtocol(
+        GraphicalHostOperatingSystem operatingSystem)
+    {
+        if (operatingSystem == GraphicalHostOperatingSystem.Windows)
+            return GraphicalDisplayProtocol.Windows;
+
+        if (!GraphicalWindowBackendConfigurator.TryGetConfiguredApi(
+                out Glfw? glfw)
+            || glfw is null
+            || !glfw.Context.TryGetProcAddress(
+                "glfwGetPlatform",
+                out nint export))
+        {
+            return GraphicalDisplayProtocol.Unknown;
+        }
+
+        int platform =
+            ((delegate* unmanaged[Cdecl]<int>)export)();
+        return platform switch
+        {
+            GlfwX11Platform => GraphicalDisplayProtocol.X11,
+            GlfwWaylandPlatform => GraphicalDisplayProtocol.Wayland,
+            GlfwWin32Platform => GraphicalDisplayProtocol.Windows,
+            _ => GraphicalDisplayProtocol.Unknown,
+        };
+    }
+
+    internal static string GetVersion(
+        GraphicalHostOperatingSystem operatingSystem)
+    {
+        if (!GraphicalWindowBackendConfigurator.TryGetConfiguredApi(
+                out Glfw? glfw)
+            || glfw is null)
+        {
+            return "unknown";
+        }
+
+        return glfw.GetVersionString() ?? "unknown";
+    }
+}