vocab: stop re-teaching a word later in the same session (239 tags)

A word tagged VOCAB in one activity was tagged again in later activities of the
same session, so the learner got the same chip repeatedly — most visibly in the
pronunciation drills, which re-listed every word from the dialogue before them
(reported: book 7 session 1-2). Rule applied: drop a VOCAB whose word was
already tagged in an EARLIER activity of that session. Repeats INSIDE one
activity are kept — those teach distinct senses ('stuck to his finger' vs
'stuck the milk in the fridge', 'shop' as verb then noun). Also dropped chips
for plurals of already-known words in book 7 session 1-2, where the drill
teaches the singular/plural pair rather than new vocabulary. No session lost
all of its vocabulary (verified).

Co-authored-by: Cursor <cursoragent@cursor.com>

book-12-lesson-2.module

@@ -149,10 +149,8 @@ LINE: That job did not pay enough money. I turned it down. {bk12-l2a-f1-02.mp3}
 VOCAB: education
 LINE: Sergeant Franklin wants his children to have a good education. He wants them to go to a good school. {bk12-l2a-f1-03.mp3}
 
-VOCAB: university
 LINE: Keith studied French when he was at the university. {bk12-l2a-f1-04.mp3}
 
-VOCAB: diploma
 LINE: Debbie received her diploma yesterday. She finished school. {bk12-l2a-f1-05.mp3}
 
 VOCAB: already
@@ -280,15 +278,12 @@ Narrator: He'll talk it over with his wife, Paula, this evening. {st-page_047_00
 
 Narrator: Meet Paula. {st-page_048_001.jpg}
 VOCAB: professional
-VOCAB: education
 Narrator: Paula is a professional in the field of education. {st-page_048_001.jpg}
 Narrator: She teaches Spanish at a high school. She has been a teacher in the same school for the last ten years. {st-page_048_001.jpg}
 VOCAB: just
 Narrator: This afternoon, Highland College just offered her a job. {st-page_048_001.jpg}
 Narrator: She would like to change jobs because it would be good for her professional growth, but the job at the college is in the evening, and that's the time she spends teaching her children. {st-page_048_001.jpg}
 VOCAB: think over | think it over
-VOCAB: discuss
-VOCAB: offer
 Narrator: She has to think it over and discuss the offer with Dan this evening. {st-page_048_001.jpg}
 
 # Source: ST §A Time for Decisions True/False
@@ -478,8 +473,6 @@ VOCAB: take
 Paula: Yes, but first, remember, I am a mother and an educator so I want to educate my children first. If I take the job at Highland College, I won't have time to teach them.
 
 VOCAB: confused
-VOCAB: accept
-VOCAB: refuse
 Dan: Now I'm confused, Paula. You've always said you need professional growth, and now that you have a chance, instead of accepting a better job, you're going to refuse it.
 
 VOCAB: decision