Select and lock a specific lecture or tutorial time

[zac-k-03]

As a student, I want to be able to select and lock a specific lecture or tutorial time so that it doesn’t change in new schedules.

• UI Interaction:
	○ Provide a clear control (e.g., a “lock” button or checkbox) next to each lecture/tutorial option in the schedule view.
	○ Allow users to click on a specific class section to mark it as "locked."
	○ Confirm the action with a visual cue (e.g., a color change or lock animation).
• Data Persistence:
	○ Store the locked status of the selected class section in the user’s profile or session data.
	○ Ensure that the locked status is retained across sessions (if applicable) and visible when the user revisits the timetable.
• Algorithm Integration:
	○ When generating new timetables, incorporate locked sections as fixed constraints.
	○ The scheduling algorithm must preserve all locked sections and only modify unlocked sections.
• Testing & Validation:
	○ Verify through unit tests that when a section is locked, it remains unchanged during schedule regeneration.

Simulate multiple schedule generations to ensure locked sections are consistently maintained.