Build the UK region list from .py's packaged area lists

changelog.d/uk-area-lists-from-py.changed.md

@@ -0,0 +1 @@
+The UK metadata's constituency and local-authority region options, and the economy region check that accepts them, read the area lists packaged with .py, without importing .py, and the Public API's own copies of those lists are removed; the region options and the regions the check accepts are unchanged.

policyengine_api/country.py

@@ -216,7 +216,9 @@ def build_microsimulation_options(self) -> dict:
                     for name, label in UK_COUNTRY_REGIONS
                 ),
             ]
-            # The economy region check reads the same cached lists.
+            # Constituencies, then local authorities, each sorted by name, from
+            # the area lists .py builds its UK region registry from. The economy
+            # region check reads the same cached lists.
             region.extend(
                 {
                     "name": f"{area_type}/{area.name}",