homeplanr v0.13.0

0.13.0 tuning: user feedback round 4 — close the inter-storey facade gap

The slab between storeys is built from ROOM polygons (the walls' INNER
faces), so along the whole facade a SLAB_THICKNESS-tall slot stayed open
between the lower storey's wall tops and the upper storey's wall bottoms
— stacked walls read disconnected, and under realistic lighting interior
light leaked out through the band ("light passing through, visible
outside"). Every UPPER storey now renders a WallBaseBand: its wall
footprints + junction patches extruded down through the slab band
(z −SLAB_THICKNESS..0), closing the perimeter flush with the storey's
own walls. Setbacks still show the honest slab edge; single-storey
documents are untouched (band renders only above ground — baselines
green). Probe-verified under the evening sun: continuous facade, no slot.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>