async getNewsletterSubscriberStats(newsletterId, options = {}) {
        try {
            // Run both queries in parallel for better performance
            const [totalResult, rawDeltas] = await Promise.all([
                // Get total subscriber count (optimized query - avoid JOIN)
                this.knex('members_newsletters as mn')
                    .countDistinct('mn.member_id as total')
                    .where('mn.newsletter_id', newsletterId)
                    .whereNotExists(function () {
                        this.select('*')
                            .from('members as m')
                            .whereRaw('m.id = mn.member_id')
                            .where('m.email_disabled', 1);
                    }),
                
                // Get daily deltas (optimized query)
                this._getNewsletterSubscriberDeltas(newsletterId, options)
            ]);

            const totalValue = totalResult[0] ? totalResult[0].total : 0;
            const total = parseInt(String(totalValue), 10);

            // Transform raw database results to properly typed objects
            const deltas = [];
            for (const row of rawDeltas) {
                if (row) {
                    // @ts-ignore
                    const dateValue = row.date || '';
                    // @ts-ignore
                    const deltaValue = row.value || 0;
                    deltas.push({
                        date: String(dateValue),
                        value: parseInt(String(deltaValue), 10)
                    });
                }
            }

            return {
                data: [{
                    total,
                    deltas
                }]
            };
        } catch (error) {
            logging.error(`Error fetching subscriber stats for newsletter ${newsletterId}:`, error);
            return {
                data: [{
                    total: 0,
                    deltas: []
                }]
            };
        }
    }
Get newsletter subscriber statistics including total count and daily deltas for a specific newsletter

@param {string} newsletterId - ID of the newsletter to get subscriber stats for
@param {Object} options - Query options
@param {string} [options.date_from] - Optional start date filter (YYYY-MM-DD)
@param {string} [options.date_to] - Optional end date filter (YYYY-MM-DD)
@returns {Promise<{data: Array<{total: number, deltas: Array<{date: string, value: number}>}>}>} The newsletter subscriber stats