Accelerate with copilot

[JHorvath-MaxetaTech]

This pull request adds several new extracurricular activities to the system and enhances the user interface to better display participant information. It also improves backend validation to prevent duplicate signups. The most important changes are grouped below:

New activities and data enhancements:

• Added six new activities to the activities dictionary in src/app.py, covering sports (Soccer Team, Basketball Club), arts (Drama Club, Art Workshop), and intellectual pursuits (Math Club, Science Olympiad), each with schedules, participant limits, and initial participants.

Backend validation improvements:

• Updated the signup_for_activity function in src/app.py to check if a student is already signed up for an activity, raising an error if so, to prevent duplicate signups.

Frontend user interface improvements:

• Enhanced the activity card UI in src/static/app.js to display a formatted list of participants for each activity, including a message when no participants are present.
• Added new CSS styles in src/static/styles.css to style the participants section, including the card, title, and list items for improved readability and visual appeal.