Fix pyrefly 1.2.0 type-check failure

[Copilot]

The backend Actions job failed after upgrading Pyrefly to 1.2.0, which rejected NewType identifiers as keys in the foreign-key validation lookup.

• Typing: Update the lookup annotation to accept runtime NewType keys without changing behavior.

check_lookup: dict[Any, CheckCallableT] = {
    StageId: check_stage_belongs_to_tournament,
    TeamId: check_team_belongs_to_tournament,
}