feat(render): Phase A8 — indoor visibility + streaming fixes batch

Lands the working A8 indoor-rendering and streaming fixes accumulated this
session. User has verified these visually to some degree (e.g. lifestone /
translucent meshes confirmed fine under the FrontFace flip; bridge / wall /
collision regressions confirmed fixed after travel); not every path has been
exhaustively gated. The cellar-flap defect remains OPEN and will be solved
the retail-faithful way via a dedicated brainstorm (see handoff docs).

Rendering core (reviewed, high confidence):
- EnvCellRenderer SSBO stride fix: upload packed Matrix4x4[] (64B) instead of
  the 80B CPU InstanceData struct the shader never expected — fixes the
  transform/texture "explosion" for any draw with >1 instance (cells that
  dedupe to a shared cellGeomId). Real root cause.
- WB-style global FrontFace(CW) + per-batch CullMode carried through the MDI
  layout (GroupKey + BuildIndirectArrays + DrawIndirectRange split into
  same-cull runs with absolute uDrawIDOffset per run).
- EntitySet partitioning (IndoorPass / OutdoorScenery / LiveDynamic) +
  WorldEntity.BuildingShellAnchorCellId so building shells scope to their
  dat-derived building cell instead of rendering everywhere.
- RenderOutsideInAcdream (look into buildings from outside) +
  CollectVisiblePortalBuildings frustum cull of portal bounds.
- Sky-when-inside-building + per-cell audit probe + GL-state probe.

Streaming / perf (test-covered; not independently code-reviewed this session):
- Near/far priority queues so near work wins over far; PromoteToNear carries
  full landblock + mesh data; LandblockEntriesWithoutAnimatedIndex avoids
  rebuilding the animated-lookup dict in the hot draw path. Fixes the
  bridge-not-appearing / missing-walls / broken-collision-after-travel
  regressions and improves post-transition FPS.

Tooling + docs:
- tools/A8CellAudit: offline dat cell/portal/building dumper (portals +
  buildings modes) — reproduces the cellar-flap investigation with no launch.
- docs/research cellar-flap root-cause + option-2 handoff (the didInsideStencil
  double-duty finding + the WB-recursive design decision + brainstorm prompt),
  entity-taxonomy, replan, issue-78 visibility investigation.

Diagnostics retained on purpose: ACDREAM_A8_DIAG_* gates, portal_stencil.vert
provisional pos.w clamp, and the probe families are kept (env-var gated, zero
cost when off) because the pending option-2 cellar-flap brainstorm needs them.
Strip in the option-2 ship commit.

Indoor branch stays behind ACDREAM_A8_INDOOR_BRANCH=1 (default off = pre-A8
visual). Build green; App tests + Core (streaming/dispatcher/loader) tests pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/AcDream.App.Tests/Rendering/Wb/EnvCellRendererTests.cs

@@ -4,6 +4,8 @@
 // GL context and are visual-verified at the render frame (Task 10).
 
 using System.Collections.Generic;
+using System.Numerics;
+using System.Runtime.InteropServices;
 using AcDream.App.Rendering.Wb;
 using Xunit;
 
@@ -114,6 +116,22 @@ public class EnvCellRendererTests
 
     // (Render() requires a GL context — visual-verified in Task 10.)
 
+    [Fact]
+    public void GpuInstanceUpload_UsesMeshModernMat4Stride()
+    {
+        // mesh_modern.vert declares SSBO InstanceData as exactly one mat4,
+        // so the GPU array stride is 64 bytes. EnvCellRenderer's CPU
+        // InstanceData also carries CellId/Flags for culling/filtering and
+        // is 80 bytes; uploading that struct corrupts every instance after 0.
+        Assert.Equal(64, Marshal.SizeOf<Matrix4x4>());
+        Assert.Equal(80, Marshal.SizeOf<InstanceData>());
+
+        var field = typeof(EnvCellRenderer).GetField("_gpuInstanceTransforms",
+            System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
+        Assert.NotNull(field);
+        Assert.Equal(typeof(Matrix4x4[]), field!.FieldType);
+    }
+
     // -----------------------------------------------------------------------
     // Pool-aliasing regression tests (2026-05-28 audit findings).
     //