feat(month): show real events with continuous multi-day bars

Replace the per-day dot summary with an event-rich grid. The ViewModel now
splits the grid into week rows and, per row, resolves all-day/multi-day
events into spanning bars (reusing the week view's layoutAllDay lane math)
and single-day timed events into per-day pills.

The grid renders as an overlay: each day gets a rounded surfaceContainer
background (matching the week/day views), spanning bars draw on top so a
multi-day event is one connected bar bridging the cells it covers, and
single-day pills fill the lane slots no bar occupies on that specific day
(top-most first) so a bar-free day isn't pushed down. Up to three rows
show per day, then a "+N" dot row. Today is a filled circle on its number;
neighbour-month days are dimmed.

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

CHANGELOG.md

@@ -8,6 +8,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 ### Added
+- The month view now shows real events in each day instead of coloured
+  dots: all-day and multi-day events render as continuous bars at the top
+  (a multi-day event is one connected bar across the days it spans, not a
+  chip per day), with single-day timed events as filled pills beneath.
+  Up to three rows show per day, then a "+N" dot indicator for the rest.
+  Each day keeps a rounded surface background, matching the week and day
+  views; today is marked with a filled circle on its number
 - 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