Fix - Prevent Duplicate Attendance Entries

[ADP-1]

This pull request resolves Issue #19 by fixing a bug where the same user's attendance was recorded multiple times if they remained in front of the camera.

🔧 Changes Made

• Modified the /start route in app.py.
• Before marking attendance, the code now fetches the list of users already present for the day.
• The add_attendance() function is only called if the identified_person's ID is not in the existing list.

How to Test

1. Register a new user.
2. Click "Take Attendance."
3. Remain in front of the camera for several seconds.
4. Verify that your name appears only once in:
   • The attendance list on the main page.
   • The corresponding Attendance-{datetoday}.csv file.

Outcome

This change ensures data integrity by guaranteeing that each user is marked present only once per day.