1A: refined clip timings (cue trimming, gap compression), 512px recomposed images, four Figure-8 panels, activity-wide Figure-5 map; SHOW_PROMPT migration + INTRO fixes for remaining lessons

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

lesson-2D.module

@@ -35,7 +35,6 @@ Cline: We didn't drive. We took a taxi. {bk04-l2d-f1-10.mp3}
 
 $SELECT Figure 2: Same or Different
 INSTRUCTION: Tap Same or Different.
-AUDIO_ONLY
 OPTION: s | Same
 OPTION: d | Different
 
@@ -76,7 +75,6 @@ ANSWER: s
 
 $SELECT Figure 3: SHE or VISION
 INSTRUCTION: Tap A for the sound of 'sh' in SHE, or B for the sound of 'z' in VISION.
-AUDIO_ONLY
 OPTION: a | SHE (/ʃ/)
 OPTION: b | VISION (/ʒ/)
 
@@ -170,7 +168,6 @@ ACCEPT: sh
 
 $SELECT Figure 5: Listening Comprehension
 INSTRUCTION: Listen to the paragraphs, then choose the true statement.
-AUDIO_ONLY
 
 PROMPT: Janet and Jim are students. She plays soccer and swims every weekend. Her brother Jim likes football and basketball. He plays different sports with his friends after class. Her mother and father like tennis. They play every evening. After dinner, Janet and Jim do their homework. They watch games on TV with their mother and father after that. They all want to watch different sports. {bk04-l2d-f5-01.mp3}
 OPTION: a | Jim and Janet don't study.