Added a firm guide rule: drop a cassette activity ONLY to dissolve a
bare word-list or remove a true duplicate; keep every other. This cut
over-dropping sharply (book-4-lesson-3: 83 -> 6 dropped clips, all the
sanctioned word-list; book-1-lesson-2: 49 -> 22). Generated the Book-1
review ST images so book-1-lesson-5 can ship. All 10 masters now live.
Co-authored-by: Cursor <cursoragent@cursor.com>
Regenerated with the firmed guide rule: a topic's vocab is now
introduced via TTS sentences (VOCAB + sentence per word), with the
cassette word-drill kept after as pronunciation reinforcement — no
cold word-list opener survives. 100% cassette coverage retained;
auto-declared dialogue speakers given proper voices.
Co-authored-by: Cursor <cursoragent@cursor.com>
