Add alembic_app revision 20260611_06_merge_location_poo_tables that builds
empty location and poo_records tables (REAL float columns, matching the
production schema and the adopt scripts' EXPECTED_*_TABLE_INFO constants).
Update APP_BASELINE_REVISION to the new head. Schema-only; data migration
is handled separately by scripts/migrate_legacy_data.py (M1-T02).