Feature: Repeat alarm tone with ascending volume for critical reminders

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Description

Add an option for reminders to repeat the alarm sound continuously (with optionally ascending volume) until the user interacts with the notification.

Use Case

For truly critical reminders (flight check-in, important meetings, medication), a single notification sound can be easily missed. This feature would make certain reminders unmissable by:

1. Playing the alarm sound repeatedly (e.g., for up to 1 minute)
2. Optionally increasing volume during that time
3. If not handled, keeping the notification visible and repeating after a configurable interval

Prior Art

Referenced from legacy repository: quarck#256

The original requester mentioned being used to this behavior from another app (Calendar Event Reminder by foobarsoft, now discontinued).

Notes

This would need careful consideration around:

• How to designate which events get this treatment (per-calendar? per-event setting?)
• Battery/resource implications of repeated alarms
• Integration with Do Not Disturb modes