Main functions
addCourse - Primary function for adding courses to schedules
addCourseByURL - Adding courses via direct URLs
User Interaction Points
TableRow - Adds action buttons to each course row
CourseCatalogInjectedPopup - Detailed course modal with add functionality
HeadingAndActions - Contains the actual "Add" button
After addCourse is called, the course is appended to the active schedule's course array. Schedule's updatedAt timestamp is refreshed and schedules array is persisted to Chrome storage. Storage change triggers automatic synchronization across extension contexts through