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>

src/AcDream.App/Rendering/Wb/BuildingLoader.cs

@@ -117,6 +117,19 @@ public static class BuildingLoader
                 }
             }
 
+            bool hasPortalBounds = false;
+            var portalMin = new Vector3(float.MaxValue);
+            var portalMax = new Vector3(float.MinValue);
+            foreach (var poly in exitPortalPolys)
+            {
+                foreach (var v in poly)
+                {
+                    hasPortalBounds = true;
+                    portalMin = Vector3.Min(portalMin, v);
+                    portalMax = Vector3.Max(portalMax, v);
+                }
+            }
+
             // WB PortalService.cs:89: skip buildings with no interior cells.
             if (envCellIds.Count == 0) continue;
 
@@ -125,6 +138,10 @@ public static class BuildingLoader
                 BuildingId         = nextId++,
                 EnvCellIds         = envCellIds,
                 ExitPortalPolygons = exitPortalPolys,
+                HasPortalBounds    = hasPortalBounds,
+                PortalBounds       = hasPortalBounds
+                    ? new WbBoundingBox(portalMin, portalMax)
+                    : default,
             };
             reg.Add(building);