- Add tier_id column with FK to subscription_tiers table - Add tier_obj relationship to VendorSubscription model - Update tier_limits property to use database tier when available - Create migration with SQLite batch mode support - Backfill tier_id from existing tier code values This enables proper database relationship between vendors and their subscription tier, instead of just storing the tier code string. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>