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/Rendering/InstancedMeshRenderer.cs

@@ -20,6 +20,7 @@
 // needs to update the shader and uniform setup at the call sites.
 using System.Numerics;
 using System.Runtime.InteropServices;
+using AcDream.App.Rendering.Wb;
 using AcDream.Core.Meshing;
 using AcDream.Core.Terrain;
 using AcDream.Core.World;
@@ -33,6 +34,20 @@ public sealed unsafe class InstancedMeshRenderer : IDisposable
     private readonly Shader _shader;
     private readonly TextureCache _textures;
 
+    /// <summary>
+    /// Optional WB adapter. When non-null and <see cref="WbFoundationFlag.IsEnabled"/>,
+    /// <see cref="EnsureUploaded"/> hands the GfxObj ref to the WB pipeline instead of
+    /// uploading into our own VAO pool. The draw loop skips sentinel entries — Task 22's
+    /// WbDrawDispatcher will eventually draw them.
+    /// </summary>
+    private readonly WbMeshAdapter? _wbMeshAdapter;
+
+    // Sentinel: a GfxObj that has been handed to the WB pipeline gets this list
+    // stored in _gpuByGfxObj. The Draw loop recognises it by reference identity
+    // (object.ReferenceEquals) and skips it — no legacy VAO draw for WB-managed
+    // objects until Task 22 wires up WbDrawDispatcher.
+    private static readonly List<SubMeshGpu> WbManagedSentinel = new(0);
+
     // One GPU bundle per unique GfxObj id. Each GfxObj can have multiple sub-meshes.
     private readonly Dictionary<uint, List<SubMeshGpu>> _gpuByGfxObj = new();
 
@@ -67,11 +82,13 @@ public sealed unsafe class InstancedMeshRenderer : IDisposable
 
     private readonly record struct GroupKey(uint GfxObjId, ulong TextureSignature);
 
-    public InstancedMeshRenderer(GL gl, Shader shader, TextureCache textures)
+    public InstancedMeshRenderer(GL gl, Shader shader, TextureCache textures,
+        WbMeshAdapter? wbMeshAdapter = null)
     {
         _gl = gl;
         _shader = shader;
         _textures = textures;
+        _wbMeshAdapter = wbMeshAdapter;
 
         _instanceVbo = _gl.GenBuffer();
     }
@@ -83,6 +100,17 @@ public sealed unsafe class InstancedMeshRenderer : IDisposable
         if (_gpuByGfxObj.ContainsKey(gfxObjId))
             return;
 
+        // Phase N.4 Task 9: when the WB foundation flag is on and we have an
+        // adapter, hand this GfxObj to the WB pipeline instead of uploading our
+        // own VAO. The sentinel entry marks "this GfxObj lives in WB now" so the
+        // draw loop knows to skip it. Task 22's WbDrawDispatcher will draw them.
+        if (WbFoundationFlag.IsEnabled && _wbMeshAdapter is not null)
+        {
+            _wbMeshAdapter.IncrementRefCount(gfxObjId);
+            _gpuByGfxObj[gfxObjId] = WbManagedSentinel;
+            return;
+        }
+
         var list = new List<SubMeshGpu>(subMeshes.Count);
         foreach (var sm in subMeshes)
             list.Add(UploadSubMesh(sm));
@@ -217,6 +245,11 @@ public sealed unsafe class InstancedMeshRenderer : IDisposable
             if (!_gpuByGfxObj.TryGetValue(key.GfxObjId, out var subMeshes))
                 continue;
 
+            // WB-managed GfxObjs have a sentinel entry; Task 22 (WbDrawDispatcher)
+            // will draw them. Skip here to avoid drawing with stale/null VAO data.
+            if (object.ReferenceEquals(subMeshes, WbManagedSentinel))
+                continue;
+
             bool hasOpaqueSubMesh = false;
             foreach (var sub in subMeshes)
             {
@@ -292,6 +325,10 @@ public sealed unsafe class InstancedMeshRenderer : IDisposable
             if (!_gpuByGfxObj.TryGetValue(key.GfxObjId, out var subMeshes))
                 continue;
 
+            // WB-managed GfxObjs — skip; Task 22 will draw them.
+            if (object.ReferenceEquals(subMeshes, WbManagedSentinel))
+                continue;
+
             bool hasTranslucentSubMesh = false;
             foreach (var sub in subMeshes)
             {
@@ -419,7 +456,10 @@ public sealed unsafe class InstancedMeshRenderer : IDisposable
 
                 foreach (var meshRef in entity.MeshRefs)
                 {
-                    if (!_gpuByGfxObj.ContainsKey(meshRef.GfxObjId))
+                    if (!_gpuByGfxObj.TryGetValue(meshRef.GfxObjId, out var cachedMeshes))
+                        continue;
+                    // WB-managed GfxObjs don't go through our instance pipeline.
+                    if (object.ReferenceEquals(cachedMeshes, WbManagedSentinel))
                         continue;
 
                     var model = meshRef.PartTransform * entityRoot;
@@ -525,6 +565,11 @@ public sealed unsafe class InstancedMeshRenderer : IDisposable
     {
         foreach (var subs in _gpuByGfxObj.Values)
         {
+            // WB-managed entries use the sentinel — no GL resources to free here;
+            // ObjectMeshManager owns those resources.
+            if (object.ReferenceEquals(subs, WbManagedSentinel))
+                continue;
+
             foreach (var sub in subs)
             {
                 _gl.DeleteBuffer(sub.Vbo);