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/verification/2026-11-06-cross-sections.md

@@ -1,6 +1,6 @@
 # Cross-sections — crowned road, gutters, sidewalk shelves
 
-Sampled 2026-11-06 from the local 3DEP DEM (`Geo/raw/dem-3dep-1m-26911-2026-11-06.tif`) with `Geo/scripts/street_section.py`. Seven sections at 40 m spacing, offsets −18 m to +18 m from the boulevard centreline (negative = south), 1 m sampling step.
+Sampled 2026-11-06 from the local 3DEP DEM (`Geo/raw/dem-3dep-1m-26911-2026-11-06.tif`) with `Geo/tools/street_section.py`. Seven sections at 40 m spacing, offsets −18 m to +18 m from the boulevard centreline (negative = south), 1 m sampling step.
 
 ## What the profile shows