feat(core): S1 one CellStruct interpretation, installed-DAT scan, retire AP-234

Campaign OVERHAUL S1 chunk B.

- CellMesh.Build's render role is deleted; CellMesh.HasDrawableGeometry
  is the exact predicate (any sides_type candidate whose resolved surface
  passes the built-EnvCell (Surface.Type & 6) != 0 test), and the
  streaming build job consumes it. Core and Content no longer carry two
  CellStruct interpretations.
- Installed-DAT scan over the complete Environment corpus (5,346
  landblocks, 729,888 cells, 8,601,560 polygons, 8,608,746 candidates):
  3,197 old-rule admissions were untextured surfaces the NoPos proxy let
  through; zero new-only; zero unexplained; zero unknown sides values;
  counts pinned as goldens against the contract's DAT hashes.
- Canonical pins: 0xF4180104 has eight ST_DOUBLE clip-map polygons and 44
  drawable side calls; the canonical NoPos surfaces are type 0x11 and are
  constructed but skipped; two independent extractions of all ten
  canonical cells hash identically.
- AP-234 retired from the divergence register (161 active rows) with
  ConstructMesh 0x0059DFA0 / DrawEnvCell 0x0059F170 / DrawMesh 0x0059D4A0.
- StipplingSurfaceEquivalenceTests no longer claims a build-time NoPos
  skip; the cell half is report-only, the building half stays pinned.
- Inventory and policy remarks updated; plan ledger records chunk A and
  the capture kit.

Core Meshing+Conformance 95/95, Content 208/208 (Lane!=Timing,
Lane!=PreparedPackage), App EnvCell/LandblockBuild/Streaming 432/432,
Release solution build 0 warnings / 0 errors.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

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

@@ -2110,6 +2110,18 @@ namespace AcDream.App.Rendering.Wb
                         indexSegments);
                 }
 
+                // OH2/S1 (docs/research/2026-09-01-overhaul/oh2-cellstruct-surface-contract.md
+                // §3.6 point 5): for a cell-shell mesh (batch.IsCellShell true),
+                // this dictionary walk groups by (Width,Height,Format) for
+                // atlas/storage packing only — it is NOT retail's ascending
+                // source-surface-index subset draw order. The resulting
+                // `renderBatches` list order is what EnvCellRenderer later
+                // replays as draw order. Recovering the exact retail order
+                // requires walking AcDream.Content.CellSurfaceSubsets.
+                // InAscendingSurfaceOrder(meshData) instead; no consumer does
+                // that yet (OH7's ordered draw stream is the intended owner) so
+                // this upload path still does not preserve retail's subset
+                // order for cell shells.
                 foreach (var (format, batches) in meshData.TextureBatches)
                 {
                     foreach (var batch in batches)