fix(transform): increase geonames object size limit and remove stale column ref

- stg_population_geonames: add maximum_object_size=40MB to read_json() call;
  geonames cities_global.json.gz is ~30MB, exceeding DuckDB's 16MB default
- dim_locations: remove stale 'population_year AS population_year' column ref;
  stg_population_geonames has ref_year, not population_year — caused BinderException

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

transform/sqlmesh_padelnomics/models/foundation/dim_locations.sql

@@ -35,7 +35,6 @@ locations AS (
     admin1_code,
     admin2_code,
     population,
-    population_year  AS population_year,
     ref_year
   FROM staging.stg_population_geonames
   WHERE lat IS NOT NULL AND lon IS NOT NULL