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/SessionPlayerComposition.cs

@@ -740,15 +740,6 @@ internal sealed class SessionPlayerCompositionPhase
             d.MovementDiagnostics,
             d.Character.MovementSkills,
             d.ViewportAspect);
-        if (d.SettingsDevTools.DevTools is { } devTools)
-        {
-            bindings.Adopt(
-                "developer player mode",
-                devTools.LateBindings.PlayerModeCommands.BindOwned(playerMode));
-            bindings.Adopt(
-                "developer command bus",
-                devTools.CommandBus.BindOwned(liveSessionSource));
-        }
         var playerModeAutoEntry = new PlayerModeAutoEntry(
             new LivePlayerModeAutoEntryContext(
                 liveSessionSource,
@@ -832,8 +823,7 @@ internal sealed class SessionPlayerCompositionPhase
             static value => value.Dispose());
 
         AcDream.UI.Abstractions.Panels.Vitals.VitalsVM? vitals =
-            d.SettingsDevTools.DevTools?.Vitals
-            ?? interaction.RetainedUi?.Vitals;
+            interaction.RetainedUi?.Vitals;
         var sessionRuntimeFactory = new LiveSessionRuntimeFactory(
             new LiveSessionPlayerRuntime(
                 d.PlayerIdentity,
@@ -893,9 +883,10 @@ internal sealed class SessionPlayerCompositionPhase
                 d.Options.LivePass ?? string.Empty));
         Fault(SessionPlayerCompositionPoint.SessionHostCreated);
 
-        Action<string>? debugToast = d.SettingsDevTools.DevTools is { } devOwner
-            ? message => devOwner.Debug.AddToast(message)
-            : null;
+        // The ImGui developer-tools debug toast sink was removed at Campaign V
+        // slice V11 along with the rest of the ImGui frontend; there is no
+        // replacement toast surface yet.
+        Action<string>? debugToast = null;
         var combatModeOperations = new LiveCombatModeOperations(
             new LiveSessionCombatModeAuthority(sessionHost),
             new LocalPlayerCombatEquipmentSource(
@@ -954,8 +945,7 @@ internal sealed class SessionPlayerCompositionPhase
             var commands = new GameplayInputCommandController(
                 new RetainedGameplayWindowCommands(
                     interaction.RetainedUi?.Runtime),
-                new DevToolsGameplayCommands(
-                    d.SettingsDevTools.DevTools?.Presenter),
+                new DevToolsGameplayCommands(),
                 runtimeDiagnostics,
                 new PlayerModeGameplayCommands(
                     d.PlayerMode,