Construction endpoints

Method	Endpoint	Description
`GET`	`/v1/construction-costs/catalog`	Source and unit catalog
`POST`	`/v1/construction-costs/estimate`	Deterministic project capex scenarios
`POST`	`/v1/construction-costs/simulate`	Seeded schedule and cost uncertainty simulation
`GET`	`/v1/construction-costs/line-items/health`	Line-item estimate service availability
`POST`	`/v1/construction-costs/line-items/estimate`	Bounded regional line-item estimate

Screening assumptions, public benchmarks, and commercial line items remain separately sourced. Simulation outputs are not investment returns.