docs(memory): the road is at 366 by itself, so the gap appears after Blender

Checked the obvious escape route and closed it: there are no duplicate Demo_Road_Hollywood actors after
several import rounds - one actor, identity transform, mesh Z -44..366. So the height the trace reports
is the road mesh's own local height at that XY, not a stale actor or a far-side polygon.

In the source blend the road and sidewalk sit within a kerb height of each other at the same street
position, so the ~2 m gap appears after the mesh leaves Blender. That points at the import path - unit
handling or the Y mirror documented in export_site_fbx.py - rather than the strip generation, and it is
the next thing to test.

MEMORY.md

@@ -540,3 +540,9 @@ Scope: facts and traps that cost time to establish. Planned work lives in [TODO.
 - **The surfaces themselves disagree:** at the player's X (-133 m) the sidewalk top is **169 cm** while `Road_Hollywood` is **366 cm** - the road sits ~2 m ABOVE the sidewalk. The player therefore lands on the road, and no sidewalk collision trick will change that, because the sidewalk is not where the road is.
 - That is a **site-data problem**, not a placement or collision one: the road and the sidewalks were generated from different passes and their heights no longer agree along this stretch.
 - **Next:** regenerate the road and sidewalks from one elevation pass in the site assembly so their surfaces meet at the kerb, then re-export and re-import (one export + one import + one 14 s probe).
+
+## 2026-11-09 — No duplicates, so the road mesh itself is at 366 there
+
+- Checked for two `Demo_Road_Hollywood` actors after several import rounds: **none**. One actor, at the origin, identity scale, mesh Z spanning -44..366 cm.
+- So the 366 cm the trace reports at the player's XY is the road mesh's own local height there, not a stale duplicate and not a far-side hit. The sidewalk slice at the same X tops at 169 cm.
+- In the source blend at the same street position both surfaces sit around 1.4-1.6 m and agree within a kerb height, so the ~2 m gap appears **after** the mesh leaves Blender - which points at the import path (unit handling, or the Y mirror noted in `export_site_fbx.py`) rather than the strip generation.