CRITICAL FIXES:
- Fixed isPureDontKnow logic in chat mode to properly exclude confusion/help requests
- Added detection for repetition frustration: 'hab ich doch schon gesagt', 'already said that'
- Enhanced confusion detection in both chat and step-by-step modes
- Added topic-specific fallback explanations for bird flight questions
- Ensures confused/frustrated children get explanations instead of more questions
This resolves the issue where children expressing confusion in chat mode were still getting Socratic questions instead of helpful explanations.
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