BREAKING CHANGE: Refactor message stream processing and think tag handling logic
- Improve automatic collapse behavior of reasoning panel
- Collapse panel immediately after reasoning content completion
- Add detection for complete think tag pairs
- Remove dependency on full content completion
- Enhance think tag processing
- Unify tag handling logic across stream and stop states
- Add robust handling for unclosed think tags
- Prevent markdown rendering errors from malformed tags
- Simplify state management
- Reduce complexity in collapse condition checks
- Remove redundant state transitions
- Improve code readability by removing unnecessary comments
This commit ensures a more stable and predictable behavior in the chat interface, particularly in handling streaming responses and reasoning content display.
