SMS Grades & BAC Calculator

What it does: - Injects a grades overview widget at the top of the SMS dashboard page - Shows a general average across all enabled subjects - Shows a card per subject with the weighted average grade, color-coded - Shows a recent grades table with the last 10 graded assignments across all subjects - Automatically discovers enrolled courses from the SMS grades page - Allows hiding/showing courses via the extension popup (persisted in local storage) How it works: 1. Authentication: The extension piggybacks on the user's existing SMS session (PHPSESSID cookie set after SAML/ADFS login via Office 365). No credentials are stored or handled by the extension. 2. Course discovery: On dashboard load, the extension fetches `grades_details.php` and parses the <select id="course_id"> dropdown to discover all enrolled courses dynamically. 3. Grade fetching: For each visible course, the background service worker fetches the course's grade page. The content script parses the HTML table to extract dates, types, descriptions, weights, and grade percentages. 4. Weighted averages: Computed as `sum(grade * weight) / sum(weight)`, skipping ungraded entries. The general average is the mean of all subject averages. 5. Course visibility: Hidden courses are stored in `chrome.storage.local` under the key `hiddenCourses`. The extension popup provides a checklist to toggle visibility.