[Feature] Make calendar colors persistent for recurring events and sync them accross devices

[kaii-tech]

Is your feature request related to a problem? Please describe.
Yes. When a user assigns a custom color to a recurring calendar appointment (like a weekly meeting), the color is only applied to that single instance of the event. It does not persist for any of the future events in that series.

Describe the solution you'd like
I would like the app to give the user an option to apply a custom color to an entire recurring series of events.

When a user changes the color of an event that is part of a series, a prompt could appear asking them to choose:

1. Apply color to "This event only"
2. Apply color to "This and all future events"

Furthermore, it would be a major improvement if these custom color settings could sync across devices (e.g., iPhone and iPad), so the calendar looks the same everywhere.

Additional context
The main reason for this request is to visually differentiate recurring university commitments. For example, it would be incredibly helpful to make all "Project Meetings" blue and all "Lab Sessions" green to make my weekly schedule easier to understand instantly.

If i rember correctly, an earlier version of the app seemed to automatically use different colors for different event types (like Lectures vs. Exercises).

This feature would be a huge quality-of-life improvement for students trying to organize their schedules. Thank you for considering it.