Slice 1 of the roof-insulation generator (ADR-0021). New `recommend_roof_insulation`
dispatcher keys on the `roof_construction_type` string: a "sloping ceiling" roof
that is uninsulated (roof_insulation_thickness 0/None) gets a single
`sloping_ceiling_insulation` Option whose overlay raises roof_insulation_thickness
to 100 mm. Pinned against the Elmhurst before→after cert 001431 at 1e-4.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>