Introduces a coordinator to manage event layout calculations,
separating this logic from rendering.
It calculates stack levels and allocates event columns for
improved visual organization of calendar events.
Moves complex layout determination logic (grid grouping, stack levels, positioning) from `EventRenderer` to a new `EventLayoutCoordinator` class.
Delegates layout responsibilities to the coordinator, significantly simplifying the `EventRenderer`'s `renderColumnEvents` method. Refines `EventStackManager` by removing deprecated layout methods, consolidating its role to event grouping and core stack level management.
Improves modularity and separation of concerns within the rendering pipeline.
