### What problem does this PR solve?
feat(search): Optimized search functionality and user interface #3221
### Type of change
- Added similarity threshold adjustment function
- Optimized mind map display logic
- Adjusted search settings interface layout
- Fixed related search and document viewing functions
- Optimized time display and node selection logic
- [x] Bug Fix (non-breaking change which fixes an issue)
### What problem does this PR solve?
feat(next-search): Implements document preview functionality
- Adds a new document preview modal component
- Implements document preview page logic
- Adds document preview-related hooks
- Optimizes document preview rendering logic
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
