_buildMrrSubquery(options) {
        let subquery = this.knex('members_subscription_created_events as msce')
            .select('msce.attribution_id as post_id')
            .sum('mpse.mrr_delta as mrr')
            .join('members_paid_subscription_events as mpse', function () {
                this.on('mpse.subscription_id', '=', 'msce.subscription_id');
                this.andOn('mpse.member_id', '=', 'msce.member_id');
            })
            .groupBy('msce.attribution_id');

        // Filter attribution_type based on post_type
        if (options.post_type === 'page') {
            subquery = subquery.where('msce.attribution_type', 'page');
        } else if (options.post_type === 'post') {
            subquery = subquery.where('msce.attribution_type', 'post');
        } else {
            // If no post_type specified, include both
            subquery = subquery.whereIn('msce.attribution_type', ['post', 'page']);
        }

        this._applyDateFilter(subquery, options, 'msce.created_at');
        return subquery;
    }
Build a subquery/CTE for mrr sum (Post-level)
(Paid Conversions Attributed to Post)
@private
@param {StatsServiceOptions} options
@returns {import('knex').Knex.QueryBuilder}