fix(render): S4 chunk 1 landing — the four comment sentences the round-2 gate-honesty lens flagged (lead correction; code unchanged)

Round 2 (9ba8f013e) passed the retail and production lenses and every gate
and mutation was reproduced by all three; the gate-honesty lens failed it
on comment truth only: the terrace-edge Fact repeated round 1's false
'PC already matched' sentence, the sixth Fact claimed a 12/4 guard split
and a preamble seed the gate does not evaluate, and WalkVisibilityMath's
scan note cited a pin that does not exist and a callers argument that
was not the real justification. A third implementer round is barred by
the campaign rule, so the lead corrected the sentences at landing.

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

src/AcDream.App/Rendering/Walk/WalkVisibilityMath.cs

@@ -232,17 +232,18 @@ public static class WalkVisibilityMath
     /// Id range: the full <c>0x0000</c>-<c>0xFFFF</c> landblock-prefix
     /// space, each landblock's cells enumerated <c>0x0100</c> through
     /// <c>0x0100 + LandBlockInfo.NumCells - 1</c> (the same range
-    /// <c>CellStructSurfaceConstructionInstalledDatTests</c>' own
-    /// independent OH2 walk uses — its pinned
-    /// <c>landblocksWithCells=3,405</c> diagnostic already agrees). What is
+    /// <c>CellStructSurfaceConstructionInstalledDatTests</c>' own OH2 walk
+    /// enumerates; that test reports its landblock count as a diagnostic
+    /// and does not pin the value). What is
     /// counted: one entry per <c>CellPortal</c> whose <c>PolygonId</c>
     /// resolves in its cell's <c>CellStruct.Polygons</c> AND has &gt;=3
     /// vertex ids that all resolve in <c>CellStruct.VertexArray</c> — an
     /// unresolvable <c>PolygonId</c>, a &lt;3-vertex polygon, or a cell
     /// whose own <c>EnvironmentId</c>/<c>CellStructure</c> does not resolve
     /// is skipped ENTIRELY (not counted toward the total or either plane
-    /// tally, matching this method's own live callers, which never see such
-    /// a polygon in the first place). Under that rule: 3,405 landblocks with
+    /// tally; no authored portal polygon has fewer than three vertices, so
+    /// the rule excludes only unresolvable data, none of which reaches this
+    /// method's live callers). Under that rule: 3,405 landblocks with
     /// cells, 1,854,237 portal polygons; 2,889 with at least one vertex on a
     /// +/-12 plane, 2,163 with EVERY vertex on the SAME plane — all 2,163
     /// are EXIT portals (<c>OtherCellId == 0xFFFF</c>; 0 interior portals