#5 fix(db): grant app user permissions on players and games tables

PostgreSQL 15+ revokes CREATE from non-superusers in public schema by default.
Child 1's migration created the tables as postgres superuser, leaving the
txt_game_scores app user with no privileges — causing "permission denied"
on every request in production.

Adds a numbered provision migration to GRANT SELECT/INSERT/UPDATE on players
and games, plus USAGE/SELECT on games_id_seq, to the app user.

Task: d1c49d59-57bd-4eba-9e22-f25a04157ad4