Implement email and in-app notifications for these Agency notifications:

1. Invoice is overdue
2. New email received
3. Task reminders
4. Client sent a message or replied

General Notifications

1. Send the primary user an email reminder 5 days before upcoming event dates
2. Alert the primary user if a new lead hasn’t been responded to within X days
3. Notify the task assignee by email when their task reaches its due date
4. Inform the primary user whenever a task they created has been completed

Acceptance Criteria

• Email and in-app notifications are triggered for the applicable events.
• Notifications are sent to the appropriate agency users.
• Email content matches sections 104–108.
  
  Remove the Upcoming event reminders in 5 days from the agency notification - it has the same one in company notification.
  
  Email content Doc - https://docs.google.com/document/d/1iukcJM2Elrre2Yr9MIeVj2jNyfQI0p9wxHtFVy2mnwQ/edit?tab=t.hpo1lskxolx1
  
  Company notification in-app notification and SMS contents - https://docs.google.com/document/d/1iukcJM2Elrre2Yr9MIeVj2jNyfQI0p9wxHtFVy2mnwQ/edit?tab=t.6fohvdhrc6sj