Replaces tradein.cad_buildings snapshot with live postgres_fdw foreign table reading gendesign.v_tradein_cad_buildings. Fixes /trade-in/api/v1/geocode/reverse 500 (Nominatim ban) and address_not_geocoded for cadastre addresses (e.g. Хохрякова 81).
Security (deep-review fixes):
- 100_tradein_fdw_role.sql: passwordless CREATE ROLE; password set by deploy.yml ALTER ROLE bootstrap reading GENDESIGN_FDW_PASSWORD from backend/.env.runtime (via psql :'pw' var → format %L — injection-safe).
- core/fdw.py: regex whitelist [A-Za-z0-9_-]{32,256} on password, ValueError without echoing value, try/rollback on commit.
- 060_postgres_fdw_extension.sql: connect_timeout='3' on FOREIGN SERVER + ALTER ADD/SET fallback.
- geocoder.py: _cadastral_forward_sync / _cadastral_reverse_sync wrapped in asyncio.to_thread.
- 100_*.sql: REVOKE ALL ON ALL TABLES/SEQUENCES/FUNCTIONS IN SCHEMA public; only GRANT SELECT on v_tradein_cad_buildings.
- pg_user_mappings query handles PUBLIC mapping (usename IS NULL).
Tests: 3 SQL-injection guards on ensure_fdw_user_mapping + rewritten cadastral suite.
