[FEAT] Improved conflict detection for assignments

[fschein]

Is your feature request related to a problem? Please describe.
Currently, the app highlights assignments in orange to indicate that a brother has a task in the same week. However, this does not provide much value when the system flags non-conflicting assignments, like the same person being assigned "Treasures" during the midweek meeting and "Prayer" during the weekend meeting. This is not a significant conflict.

Describe the solution you'd like

1. The app should show the orange color only when there is an actual conflict—when the same assignment is given in consecutive weeks.

• For example, if "Treasures" is assigned to John this week and again the following week, the app should highlight it in orange and display a tooltip (maybe in an icon like ⚠️) with the message: "Already assigned in the previous week."

2. If a person is assigned multiple roles in the same meeting, regardless of the task, the system should highlight the conflict in red and provide a tooltip with the message: "Already assigned in this meeting." (with an icon like 🔴?)

This feature would be particularly valuable for managing assignments like duties (e.g., hall overseer, audio/video, etc.), ensuring that there are no overlaps. A brother assigned to serve as a hall overseer should not be assigned to "Watchtower reader" in the same week, and those working in audio/video should not be given a talk.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Proper planning is required to ensure the conflict detection is comprehensive, as it will be a highly valuable feature for managing assignments in the Organized app.
The app should alert users about potential conflicts, but it should also allow the user to assign someone to two conflicting tasks if necessary