phase(N.4) Task 9: real WB pipeline bring-up + InstancedMeshRenderer routing

WbMeshAdapter now actually constructs the WB pipeline:
- OpenGLGraphicsDevice(gl, logger, DebugRenderSettings)
- DefaultDatReaderWriter(datDir) — opens its own file handles for now
  (memory cost ~50-100MB of duplicate index caches, acceptable for
  foundation work per plan Adjustment 1)
- ObjectMeshManager(graphicsDevice, dats, NullLogger)

InstancedMeshRenderer.EnsureUploaded routes through the adapter when
ACDREAM_USE_WB_FOUNDATION=1 is set; uses a WbManagedSentinel entry
in the local cache to mark "this GfxObj lives in WB now". CollectGroups
skips sentinel entries; both Draw passes skip them; Dispose skips them
(no GL resources to free — ObjectMeshManager owns those). Task 22's
WbDrawDispatcher will eventually draw WB-managed objects. With flag
off, behavior is byte-identical to before.

WbMeshAdapter constructor signature changed from (GL, DatCollection,
Logger) to (GL, string datDir, Logger). Updated tests to use
CreateUninitialized() for behavior tests and single null-GL guard test
for constructor validation. GameWindow updated to pass _datDir and to
wire _wbMeshAdapter into InstancedMeshRenderer.

AcDream.App.csproj gets direct ProjectReferences to WorldBuilder.Shared
and Chorizite.OpenGLSDLBackend — project refs are not transitive in
.NET, so AcDream.App must list them explicitly even though AcDream.Core
already references them.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/AcDream.App/AcDream.App.csproj

@@ -26,6 +26,12 @@
     <ProjectReference Include="..\AcDream.Core.Net\AcDream.Core.Net.csproj" />
     <ProjectReference Include="..\AcDream.UI.Abstractions\AcDream.UI.Abstractions.csproj" />
     <ProjectReference Include="..\AcDream.UI.ImGui\AcDream.UI.ImGui.csproj" />
+    <!-- Phase N.4 Task 9: WbMeshAdapter constructs the WB GL pipeline directly.
+         AcDream.Core already references these projects, but project references are
+         not transitive in .NET — AcDream.App must list them explicitly to compile
+         against Chorizite.OpenGLSDLBackend and WorldBuilder.Shared types. -->
+    <ProjectReference Include="..\..\references\WorldBuilder\WorldBuilder.Shared\WorldBuilder.Shared.csproj" />
+    <ProjectReference Include="..\..\references\WorldBuilder\Chorizite.OpenGLSDLBackend\Chorizite.OpenGLSDLBackend.csproj" />
   </ItemGroup>
   <ItemGroup>
     <None Update="Rendering\Shaders\*.*">