expand db schema to include more details from BOSS

[davidlhw]

after scraping data from BOSS via this link format:
https://boss.intranet.smu.edu.sg/ClassDetails.aspx?SelectedAcadTerm={TERM}&SelectedClassNumber={CLASS}

Proposed changes to current schemas

course schema:

• add course_area: str, example:
  
• add enrolment_requirements: str, example:
  

class schema:

• every AY+term has a unique class by course code & section
• rename label to section
• class-acad_term is a 1-1 relationship
• add acad_term: FK reference to acad_term
• add grading_basis with possible values: 'pass/fail' | 'graded'
• add class_time
• add course_outline_url: example link - the course outline, though confusingly named, is unique to the class and not the course
• add boss_id: example 1228

Proposed new schemas

acad_term schema:

• id str, example: 'AY202425T2'
• acad_year_start: 2024
• acad_year_end: 2025
• term: '3A'
• boss_id: 2420

class_timing schema:

• class-class_timing is a 1-N relationship
• class: FK reference to class
• start_date
• end_date
• day_of_week
• start_time
• end_time
• venue
• professor_id

class_exam_timing schema:

• class-class_exam_timing is a 1-N relationship
• class: FK reference to class
• date
• day_of_week
• start_time
• end_time
• venue NULLABLE

class_availability schema:

• bid_window-class_availability is a 1-1 relationship
• bid_window: FK reference to bid_window
• total
• current_enrolled
• reserved
• available

bid_window schema:

• bid_window-acad_term is a 1-1 relationship
• acad_term: FK reference to acad_term
• round
• window

bid_result schema:

• bid_result-bid_window is a 1-1 relationship
• bid_result-class is a N-1 relationship
• bid_window: FK reference to bid_window
• class: FK reference to class
• vacancy: unsure what this means in BOSS, but we'll retain for future reference
• opening_vacancy: unsure what this means in BOSS, but we'll retain for future reference
• before_process_vacancy: equal to available value in the same bid_window, ie number of seats available to be bidded for
• d_i_c_e: how many successful DICE (aka Drop If Course Exceeds) for this class in this bid window
• after_process_vacancy: number of seats left available for bidding after concluding this window
• enrolled_students: current total number of enrolled students for this class
• bid_median: the median bid for this class in this window
• bid_min: the min bid for this class in this window