- Add asyncpg connection pool (db/pool.py) with JSONB codec registration
- Add schema.sql with users, clients, dropdown_categories, export_templates, sheets tables
- Add migrate_json.py one-time migration script for existing JSON data
- Rewrite user_store, sheets/manager, api/clients, api/dropdowns, api/export as async DB-backed
- Update all callers (auth, sheets, admin, ai_command, export) to await async functions
- Add postgres:16-alpine service to docker-compose with named volume and health check
- App container depends_on postgres; DATABASE_URL injected via env
- Schema applied automatically on startup; global categories seeded if DB is empty
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>