feat(render): Campaign V slice V11 commit 1 - delete ImGui, Studio, and the DevTools frontend

The ImGui developer-tools stack (AcDream.UI.ImGui), UI Studio
(src/AcDream.App/Studio), and the DevToolsFramePresenter/
SettingsDevToolsCompositionPhase ImGui composition machinery are removed.
Vulkan never composed a DevTools frontend (DevToolsEnabled already forced
false whenever the backend was Vulkan); this commit makes that permanent by
deleting the only implementation rather than leaving a dead branch behind.

What moved: Studio/SampleData.cs is a live production dependency
(InteractionRetainedUiComposition's character-sheet fallback, plus three
UI.Layout test files) - git mv'd to src/AcDream.App/UI/Layout/SampleData.cs,
namespace AcDream.App.UI.Layout, and trimmed to the SampleCharacter API that
is actually still called (BuildObjectTable/AddItem/AddEquipped/the item-guid
and icon constants had zero callers left once the Studio fixture provider
that used them was deleted).

What survives as backend-neutral seams, per the tests that still exercise
them: IDevToolsFrameLifecycle (moved into RenderFramePreparationController.cs,
now always bound to null), IFramebufferDevToolsTarget/FramebufferDevToolsBinding
in FramebufferResizeController.cs (its concrete DevToolsFramebufferTarget
adapter is deleted), and IDevToolsGameplayCommands in
GameplayInputCommandController.cs (DevToolsGameplayCommands becomes a
documented no-op instead of forwarding to the deleted presenter). A follow-up
re-homes Settings/Debug onto the retained UI through IPanelRenderer; until
then keybind remapping falls back to editing keybinds.json.

DevToolsEnabled is now `private const bool DevToolsEnabled = false`.
RuntimeOptions.DevTools is unchanged and still reaches VulkanGraphicsContext
for the optional debug-utils extensions; Program.cs now logs one line when
ACDREAM_DEVTOOLS=1 explaining that the ImGui UI is gone and the flag is
Vulkan-only now.

Removed: AcDream.UI.ImGui (project + ImGui.NET/Silk.NET.OpenGL.Extensions.ImGui
package refs), src/AcDream.App/Studio (minus SampleData.cs),
DevToolsFramePresenter.cs and everything only it constructed
(ISettingsDevToolsCompositionFactory, RetailSettingsDevToolsCompositionFactory,
DevToolsCompositionOwner, IGameWindowSettingsDevToolsPublication,
SettingsDevToolsOptionalDependencies, the "developer tools" shutdown-ledger
stage and its DevTools-typed fields on IngressShutdownRoots/
RenderShutdownRoots), the ui-studio Program.cs verb, and the cimgui native
manifest entries in GraphicalHostPlatformServices. GameWindow.cs's DevTools
composition branch, its _vitalsVm/_debugVm/_devToolsComposition/
_devToolsFramePresenter/_devToolsCommandBus fields, and every settingsDevTools
.DevTools?.* access across FrameRootComposition.cs/SessionPlayerComposition.cs
are gone with it.

Build green; complete Release solution suite 8,830 / 5 skips (App Tests
4,097/3 skips run standalone - one #250-family zero-allocation test flakes
under the full parallel `dotnet test AcDream.slnx` run, a pre-existing,
documented class unrelated to this change).

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

src/AcDream.App/Composition/FrameRootComposition.cs

@@ -433,16 +433,17 @@ internal sealed class FrameRootCompositionPhase
                 // Campaign V slice V6j: no debug-line renderer on the Vulkan arm.
                 // DrawAndPublish flushes it INSIDE the world phase and that
                 // renderer opens its own pass, which the frame's one backbuffer
-                // pass forbids. The collision-wireframe toggle is DevTools-only
-                // and DevTools is not composed there, so nothing is lost —
-                // composing it would throw on the first wireframe frame rather
-                // than silently misdraw (plan §5.5.14 item 7).
+                // pass forbids. The collision-wireframe toggle was DevTools-only
+                // and the ImGui DevTools frontend is gone as of Campaign V slice
+                // V11, so nothing is lost — composing it would throw on the
+                // first wireframe frame rather than silently misdraw (plan
+                // §5.5.14 item 7).
                 gl is not null ? foundation.DebugLines : null,
                 d.PhysicsEngine,
                 d.PlayerMode,
                 d.PlayerController,
                 d.DebugVmRenderFacts,
-                settings.DevTools is not null);
+                debugVmConsumerActive: false);
             var worldScenePasses = new WorldScenePassExecutor(
                 worldPassSurface,
                 worldFrameGlState,
@@ -570,11 +571,15 @@ internal sealed class FrameRootCompositionPhase
                 live.PaperdollPresenter,
                 live.CreatureAppraisalPresenter),
             retainedGameplayUi,
-            settings.DevTools?.Presenter,
+            // The ImGui developer-tools frontend was removed at Campaign V
+            // slice V11; this optional hook is unbound until a follow-up
+            // re-homes it onto the retained UI (IDevToolsFrameLifecycle stays
+            // as the seam).
+            devTools: null,
             privateScreenshot);
         var framePreparation = new RenderFramePreparationController(
             renderFrameResources,
-            settings.DevTools?.Presenter,
+            devTools: null,
             renderWeatherFrame);
         IRenderFramePostDiagnosticsPhase postDiagnostics =
             renderSceneShadowComparison is not null
@@ -602,8 +607,7 @@ internal sealed class FrameRootCompositionPhase
             privatePresentation,
             live.FrameDiagnostics,
             postDiagnostics,
-            (IRenderFrameFailureRecovery?)settings.DevTools?.Presenter
-                ?? NullRenderFrameFailureRecovery.Instance);
+            NullRenderFrameFailureRecovery.Instance);
         Fault(FrameRootCompositionPoint.RenderRootCreated);
 
         var liveFrameCoordinator = new RetailLiveFrameCoordinator(