Best Ever ranking revamp

See slack thread: https://metaculus.slack.com/archives/C011Z8VPWUC/p1767887202669549

Make the algorithm that updates "Current Rank" and "Best Ever" reruns history (simulating once per month or week - dealer's choice).

Ideally, don't actually update the values in the db until the history rerun is complete - some refactoring would be required to achieve this.

During this task, also fix a minor bug where the filtered LeaderboardEntrys aren't the right ones.

    # Look only at leaderboards which are finalized
    relevant_entries_qs = LeaderboardEntry.objects.filter(
        leaderboard__finalized=True,
        leaderboard__project__type__in=[Project.ProjectTypes.SITE_MAIN, Project.ProjectTypes.TOURNAMENT],
        leaderboard__project__visibility=Project.Visibilty.NORMAL,
        leaderboard__project__default_permission=ObjectPermission.FORECASTER,
    )