fix- multiple issues in backend

[LalitDeore]

Fixes:

1. Store the AI usage alert email boolean in the database instead of the cache.
2. Send the last 365 days of data in the Get Stats API instead of only the last 60 days.
3. Do not trim daily statistics to the last 60 days if pushing stats to the GCS bucket fails for any reason. This is safety mechanism to prevent losing past statistics.