geo: one tool directory, one unit boundary, per-asset provenance

Geo/tools/ is now every geographic script, with Geo/README.md documenting each
one; the Blender-side builders moved beside their outputs in Art/blender/*/ and
import their helpers from Geo/tools/osm_common.py.

That module gains to_unreal_local() and to_blender_local(): the only place in the
repository that multiplies metres by 100, so a second silent scale cannot be
introduced. block_height_report.py adds height provenance for the block — 3 of
15 buildings have no height data and render at a placeholder 6.4 m.
asset_metadata.py writes and audits <asset>.geo.json sidecars; four now exist
(hero-facade, terrain, street, blockout) and the audit recomputes each centre from
the origin, failing anything that disagrees.

Geo/manifests/2026-11-06-3dep-dem.md

@@ -35,7 +35,7 @@ Min 110.46 m, max 127.73 m, mean 117.43 m over the 550 × 350 m window — a 17.
 
 ## Reading the file
 
-`Geo/scripts/dem_stats.py` parses it with the standard library. GDAL cannot run on the host (its flatpak libraries do not resolve outside the sandbox), and the exported TIFF is **tiled**, not strip-organised — a strip reader silently scrambles the rows. If another tool misreads it, suspect the tile layout before the data.
+`Geo/tools/dem_stats.py` parses it with the standard library. GDAL cannot run on the host (its flatpak libraries do not resolve outside the sandbox), and the exported TIFF is **tiled**, not strip-organised — a strip reader silently scrambles the rows. If another tool misreads it, suspect the tile layout before the data.
 
 ## Open