Enhanced SlotExtractor with comprehensive time references, unit inference, and action extraction improvements

- Added extensive time reference patterns (tomorrow, this morning/afternoon/evening, this/next week/month, recently, all time, this/last year)
- Separated 'now' as distinct time reference from 'today'
- Refactored extractAction into intent-specific functions (extractTimerAction, extractMediaAction, extractAppAction, extractPhoneAction)
- Enhanced extractUnit with context-based inference for stress (score), blood oxygen (percent), sleep (hours), sleep quality (score), distance, calories, and walking movement
- Removed weight unit inference as requested
- Improved slot extraction accuracy for different intent types

Author: tanmaypawar-noise