feat(drawer): add View section to switch Month/Week/Day

The slide-out panel gains a "View" section mirroring the top-bar switcher
pill: three NavigationDrawerItems (Month/Week/Day) with the current view
highlighted; tapping one selects that view and closes the drawer. The pill
stays as-is for quick cycling.

Centralise each view's label + icon as labelRes/icon extensions on
CalendarView so the pill and the drawer share one mapping. The drawer's
"Today" jump is dropped — the top-bar Today action and error-state retry
still cover it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+- The slide-out panel now has a "View" section to switch between Month,
+  Week, and Day, mirroring the top-bar switcher pill — tapping a view
+  selects it and closes the drawer. The current view is highlighted
+
 ### Fixed
 - Typing in the event title, location, and description fields no longer
   makes the cursor jump around: the form state's round-trip to the UI was