Stage 2a of epic #1953: backend service + endpoint for live economic recompute
driven by the interactive 3D massing (Stage 2b debounced sliders).
- teap.py: add pure synthesize_teap_from_program(total_footprint_sqm, floors,
site_area_sqm, housing_class, sections) — builds a TEAP from the SCALAR
aggregate footprint × floors, mirroring synthesize_teap_from_buildability and
reusing the same shared norm constants (_OFFICE_SHARE_OF_GFA / _EFFICIENCY_BY_CLASS
/ _AVG_APARTMENT_SQM / _PARKING_PER_APARTMENT) — single source of truth.
- schemas/concept.py: add MassingProgram (program contract, optional pre-resolved
market_price_per_sqm + parcel_centroid_wkt) and MassingRecomputeOutput (teap + financial).
- api/v1/concepts.py: add POST /api/v1/concepts/recompute — synthesize TEAP → run
the existing pure compute_financial. FAST path uses body market_price_per_sqm
(no DB); else _lookup_market_price by centroid via run_in_threadpool; else class norm.
- tests: synthesize_teap_from_program (gfa math, parity with compute_teap, class
efficiency, sections no-op) + endpoint (200, coherent output, price passthrough
skips DB, DB fallback, class-norm default, floors validation).
