phase(N.4) Tasks 22+23 fixup: trigger WB mesh loads + correct SurfaceId source

Task 26 visual verification surfaced three bugs in the dispatcher.
Two are fixed here; the third is documented as a remaining issue.

1. WB's IncrementRefCount only bumps a usage counter — it does NOT
   trigger mesh loading. Fixed in WbMeshAdapter.IncrementRefCount:
   call PrepareMeshDataAsync(id, isSetup: false) on first registration.
   Result auto-enqueues to _stagedMeshData (line 510 of WB's
   ObjectMeshManager) which Tick() drains onto the GPU.

2. EntitySpawnAdapter never registered per-instance entity meshes
   with WB. LandblockSpawnAdapter only registers atlas-tier
   (ServerGuid == 0); per-instance entities fell through. Fixed by
   adding optional IWbMeshAdapter constructor param + tracking unique
   GfxObj ids per server-guid for IncrementRefCount on OnCreate /
   DecrementRefCount on OnRemove.

3. WbDrawDispatcher.ResolveTexture used batch.SurfaceId which WB
   never populates (line 1746 of ObjectMeshManager only sets
   batch.Key — the TextureKey struct that has SurfaceId). Switched
   to batch.Key.SurfaceId.

Plus diagnostic counters (ACDREAM_WB_DIAG=1) for entity-seen / drawn
/ mesh-missing / draws-issued counts.

Status: with these fixes the dispatcher now issues real draw calls
(~16K/frame, validated via diagnostic). However visual verification
shows characters appear "exploded" (parts spaced too far apart) and
scenery (trees/rocks/fences/buildings) does not appear. Root cause
analysis pending — Adjustment 7 in the plan documents the deferred
work. Flag stays default-off; legacy renderer remains the
production path.

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

src/AcDream.App/Rendering/GameWindow.cs

@@ -1487,7 +1487,7 @@ public sealed class GameWindow : IDisposable
                         new NullAnimLoader());
                 }
                 wbEntitySpawnAdapter = new AcDream.App.Rendering.Wb.EntitySpawnAdapter(
-                    _textureCache, SequencerFactory);
+                    _textureCache, SequencerFactory, _wbMeshAdapter);
                 _wbEntitySpawnAdapter = wbEntitySpawnAdapter;
             }
             _worldState = new AcDream.App.Streaming.GpuWorldState(wbSpawnAdapter, wbEntitySpawnAdapter);