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-10-lesson-2.module

@@ -438,7 +438,6 @@ INTRO: Meet Jane and her favorite neighbor, Mrs. Wright — sixty-five years old
 INSTRUCTION: Listen and repeat each line.
 REPEAT
 
-VOCAB: neighbor
 LINE: Mrs. Wright and I live in the same apartment building. She's my favorite neighbor.
 
 VOCAB: downstairs
@@ -447,7 +446,6 @@ LINE: She lives in a downstairs apartment.
 VOCAB: upstairs
 LINE: I live upstairs.
 
-VOCAB: alone
 LINE: She's 65 years old and no one lives with her. She lives alone.
 
 LINE: Sometimes we go shopping together.
@@ -466,7 +464,6 @@ LINE: One day I wrote down my phone number and stuck it on her phone table.
 
 LINE: I told her to call me when she needed something. She was pleased and said, "Thank you."
 
-VOCAB: supper
 LINE: Last Friday, she asked me to have supper with her.
 
 LINE: I went to her apartment at 7:00 p.m. Mrs. Wright is a very good cook. She cooked some delicious chicken with potatoes. I really enjoyed my supper.