Retrieve apps with the largest recent spikes in notification activity.

<br/>This endpoint compares the number of notifications sent by each app in the<br/>last 7 days to the previous 7 days. It returns apps with the highest relative<br/>increases, prioritizing those that had no activity in the previous week.<br/><br/>The results are sorted as follows:<br/>1. Apps with 0 notifications in the previous 7 days and >0 in the last 7 days,<br/> sorted by raw count in the last 7 days.<br/>2. Remaining apps sorted by their increase ratio (last_7_days / previous_7_days).<br/><br/>