Course slide download: check public static site before needing browser automation

When a user asks to download lecture slides via a browser extension and the extension is disconnected, first curl the public course page (many university Sphinx/static course sites return 200 without login) and grep the hrefs. If there are no slide links (slides are behind the LMS), say so plainly and work from the PDFs already in ~/Downloads (past exams + solutions are the highest-value prep material) rather than stalling. Also check the syllabus for the exam date: in this case the exam was the same day, so being fast mattered more than being complete. For exam cheatsheets, use the solution keys to pull out recurring question types (cache tag/index/offset, AMAT, PLRU, rename/ROB tables, reservation-station ready logic) and double-check any derived examples (e.g., trace PLRU bit conventions by hand) before writing them down.