Introduces dedicated TypeScript interfaces for all drag-and-drop event payloads, enhancing type safety and developer experience.
Centralizes drag event detection and emission within `DragDropManager`. Refactors `AllDayManager`, `HeaderManager`, and `EventRendererManager` to subscribe to these typed events, improving decoupling and clarifying responsibilities.
Resolves known inconsistencies in drag event payloads, especially for all-day event conversions. Adds a comprehensive analysis document (`docs/EventSystem-Analysis.md`) detailing the event system and planned improvements.
