chapter-to-synced-lecturelisted

# Chapter to synced lecture The author lectures on his own chapter — his voice, with a picture that moves where he points — for someone who bought the book and wants to be taken through this chapter for the first time. `references/teaching.md` is the contract: the goal, the one rule, five principles. Read it before anything else. ## The run ``` ┌─ nothing at <book-dir>/lectures/<slug>/ ──▶ BUILD it <chapter.pdf> ───┤ └─ it is already there ───────────────────▶ REVISE it BUILD 1 READ extract.py ─▶ extract/ the text, the figures, the pages to look at 2 PLAN plan.md the teaching decisions, never shown 3 SLIDES lecture.src.html ─▶ lecture.html ─▶ screenshots · page_index.py --text 4 SCRIPT script.md ─▶ lint.py ─▶ cold-read review ─▶ fix ─▶ lint.py 5 RECORD build_audio.py ─▶ audio/ + cues/ ─▶ lint.py ─▶ open.py ─▶ the user listens REVISE read the script's header, the one part, that part's frames teach the doubt, in the chat, until the listener says it lands edit script.md for words, lecture.src.html for a slide build only what changed — that part's audio, or --recue, or the page ``` A build is one shot from PDF to a lecture open in the browser, and `open.py` prints where the time went. Nothing is shown for approval on the way; the approval is the listening at the end. Nothing is reported beyond one sentence if