Chosen planning designation checks

The planning designation checks you choose, for one location, in one call. `checks` is any of: article_4, brownfield, ancient_woodland, heritage_at_risk, tpo, aqma, scheduled_monument, sssi, agricultural_land, flood_risk, green_belt, listed_buildings, aonb, national_park, conservation_area — omit it for all fifteen. Each check reports its own result, and one that could not be read says `status: unknown` rather than disappearing. Use `planning_designations` for the fixed bundle of thirteen; use this when you need SSSI or agricultural land grade, or only two or three checks. Give either `postcode` or `location` as "lat,lng". UK only.