Encounter has two FKs to pokemon (pokemon_id and current_pokemon_id),
so the reverse relationship needs an explicit foreign_keys argument.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Set up PostgreSQL database layer with async SQLAlchemy 2.0 and asyncpg driver.
Implements 6 core tables (games, routes, pokemon, route_encounters, nuzlocke_runs,
encounters) with foreign keys, indexes, and an initial Alembic migration.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
