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.

AGENTS.md

@@ -39,7 +39,7 @@ The initial release is **`0.1.0`**: a walkable exterior demo around **6840 Holly
 - Track `.uasset`, `.umap`, `.blend`, and large source binaries with LFS.
 - Ignore `Binaries/`, `Intermediate/`, `Saved/`, and Derived Data Cache.
 - Never commit Unreal Engine source, credentials, or non-redistributable assets.
-- Planned remote repository: `https://git.allucanget.biz/zwitschi/gig-line.git`. Do not assume it is configured or available.
+- Active remote repository (`origin`): `https://git.allucanget.biz/zwitschi/gig-line.git`. Verify connectivity before use.
 
 ## Release Policy