feat(bot): better exam followup prompt

backend/src/bot/modules/ai/prompts.py

@@ -15,8 +15,8 @@ When asked for DETAILS on a specific problem (or a problem number):
 - This is also true if you get a summary, and then problem number is asked"""
 
 EXAM_FOLLOW_UP = """Look at the problem set image and list ALL problem numbers as
-options.
-If problems have sub-parts (a, b, c), list as: 1a, 1b, 2a, etc.
+ options. Split by subparts ONLY if they are totally different tasks, not the steps of
+ one.
 If there are multiple problem sets/sheets, break it down logically and specify set,
 for example Group A: 1, Group A: 2a, Group B: 2b, etc.
 Or, Theory: 1, Theory: 2a, Practice: 1, etc.