Replaces date-fns library with day.js to reduce bundle size and improve tree-shaking
- Centralizes all date logic in DateService
- Reduces library footprint from 576 KB to 29 KB
- Maintains 99.4% test coverage during migration
- Adds timezone and formatting plugins for day.js
Improves overall library performance and reduces dependency complexity
Adds comprehensive tests for the AllDayManager, covering various overlap scenarios.
Tests ensure correct row and column assignments for all-day events based on date ranges and overlaps.
Replaces individual event layout calculation with batch calculation for improved performance and test coverage.