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-5-lesson-4.module

@@ -1122,7 +1122,6 @@ INTRO: Two position words before we go on: between is for two things; among is f
 INSTRUCTION: Listen and repeat the sentences.
 REPEAT
 
-VOCAB: among
 LINE: Tom is a tall boy. Here he is among his friends. {st-page_113_001.jpg}
 
 VOCAB: between
@@ -1237,7 +1236,6 @@ LINE: Dick is having a cup of coffee.
 VOCAB: glass
 LINE: Harry is having a glass of tea.
 
-VOCAB: dessert
 LINE: They will have dessert in a few minutes.
 LINE: The dessert menu is coming up next.
 LINE: What will Dick have for dessert? What will Harry have?
@@ -1271,7 +1269,6 @@ ID: l4-s20
 INTRO: Here's what everyone wants from the menu. Read the sentences.
 INSTRUCTION: Read the sentences.
 
-VOCAB: dish
 LINE: Harry wants a dish of chocolate ice cream.
 LINE: Dick wants a piece of apple pie with ice cream.
 LINE: I want some chocolate chip cookies.