feat: complex analytics

[elijaholmos]

• extends feat: simple analytics #88
• store a json file for each day
• send a daily report in private discord channel at 00:00 local time (or another time when activity is expected to be low)
• track the following metrics:
  • total notifs sent
  • notifs sent per category (announcement, grade, disconnect, etc)
  • notifs sent per class
  • notifs sent per user
• aggregations and combinations of all of the above metrics (eg number of announcement notifs for student X's class Y)
• bonus: generate a fancy chart that shows notifs over time for a daily period??