Slice 2 (ADR-0021). `recommend_roof_insulation` now owns the loft branch as the
fallback — a plain pitched loft, a thatched roof (the covering doesn't block
insulating the loft floor), or an unlodged roof type all take loft (joist)
insulation at 300 mm when `roof_insulation_thickness == 0`. Sloping is tested
first; a no-access roof gets nothing. Retired the standalone
`recommend_loft_insulation`; the orchestrator and its tests now call the
dispatcher.
Pinned: thatch before→after (None→300) reproduces at 1e-4; the existing loft pin
still holds through the dispatcher. Behaviour-preserving on the golden cohort
(roof measure unchanged: none across all 57) — the dispatch is strictly more
precise (won't fire loft on a sloping/no-access roof).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
