feat: headless Blosm blockout of the demo block

Tools/blosm_blockout.py imports the committed extract in 3Dsimple mode and
reports per-building dimensions so a units failure is visible in the log. The
result (87 meshes) is committed as the blockout baseline: hero 25.68 x 54.88 x
14.50 m against 25.75 x 54.88 m of OSM geometry, so the import is 1:1 metres.

Two headless defects needed working around: the asset-directory check that
fires before mode is honoured, and an empty default-level table sending the
add-on down a broken relative import. Member fetching stays off so the import
does not depend on Overpass.

ROADMAP.md

@@ -31,7 +31,7 @@ Status detail in [Docs/setup.md](Docs/setup.md); workstation audit in [Docs/envi
 - [x] Download the 3DEP 1 m DEM for the demo bounds, reproject it to EPSG:26911 with the recorded origin and vertical datum, and record the source, clip bounds, and checksum in `Geo/`.
 - [x] In QGIS, set a suitable local projected CRS (e.g. EPSG:26911) and record a local origin. EPSG:26911, origin and projected easting/northing are recorded in `Geo/manifests/local-origin.md` with PROJ 9.9.0 control points; QGIS 4.2.3 is installed for the DEM reprojection step.
 - [x] Verify the address, building footprints, and demo boundaries for 6840 Hollywood Blvd against source data.
-- [ ] Import OSM blockouts through Blosm; clean and detail them in Blender.
+- [-] Import OSM blockouts through Blosm; clean and detail them in Blender. Imported 2026-11-06 (`Art/blender/blockout/blockout-2026-11-06.blend`, 87 meshes, scale verified 1:1 against OSM); cleaning and detailing not started.
 - [ ] Preserve geographic coordinates in metadata; define explicit meter→centimeter conversion to local Unreal coordinates.
 
 ### Asset production