build_prediction_target assembles an EPC-less Property's PredictionTarget from
its identity (postcode), resolved coordinates, and Landlord-Override attributes
(property_type / built_form / wall_construction). The eligibility GATE: a Property
whose property_type is unknown returns None — never sized from a mixed-type
cohort (ADR-0031). property_type is the hard cohort filter.
The override attributes are read through a PredictionTargetAttributesReader port
(stub seam) — the real adapter (a read over property_overrides) is being built
separately by the team; ingestion wiring depends on the abstraction and tests
substitute a fake. 2 tests (assembly + gate); pyright strict clean.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
