The backfill service (app/services/yandex_address_backfill.py) + its manual
admin endpoint already exist, but it was never wired into the in-app scheduler
— so residual street-only yandex listings (no house number) were only fixed
on manual trigger. Add a recurring scheduler task: trigger_yandex_address_backfill_run
mirrors trigger_cian_backfill_run (claim run + mark done/failed), new task
wrapper app/tasks/yandex_address_backfill.py delegates to the existing
backfill_yandex_addresses(), dispatch branch + seed migration 091 (window
02:00-03:00 UTC, ON CONFLICT(source) idempotent). EKB-only (region_code=66).
Refs #855, #726
