Calendar · Months: a month view, a year view, event chips and cards

CalendarMonthView lays a month in week rows. An event across days lies
over them as a bar in the first free lane, cut at the week's edge;
the rest sit by the hour as chips, and a crowded day keeps the rest
behind "N more". Arrows move a day, Page keys turn the month, and
Enter or a double press opens the day; the cursor holds through the
owner's echo of a turn. Days sit at sevenths of their row, as the bars
do, so text never widens a column.

YearView shows twelve small months; a day with something on it wears a
dot in its first event's hue. EventChip is an event in a line and
EventCard a block with its hours and place. MiniCalendar points to
forms::Calendar. Palette::hue is now the one home for a chart color by
index, for mail labels and events alike.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tasks/ch21-30.md

@@ -385,22 +385,31 @@
 - [x] LabelPicker
 - [x] SnoozePicker
 
-## T30 Calendar — `src/calendar`
+## T30a Calendar · Months — `src/calendar`
+
+- [x] CalendarMonthView
+- [x] YearView
+- [x] MiniCalendar → `forms::Calendar`
+- [x] EventCard / EventChip
+
+## T30b Calendar · Time grid
 
-- [ ] CalendarMonthView
 - [ ] CalendarWeekView
 - [ ] CalendarDayView
-- [ ] AgendaView
-- [ ] YearView
-- [ ] MiniCalendar → `forms::Calendar`
-- [ ] EventCard / EventChip
-- [ ] EventEditor
-- [ ] EventPopover
 - [ ] TimeGrid — drag to create, resize
 - [ ] AllDayRow
 - [ ] CurrentTimeIndicator
-- [ ] RecurrenceEditor
-- [ ] AvailabilityPicker
 - [ ] TimezoneOverlay
-- [ ] ReminderPicker
+
+## T30c Calendar · Agenda and people
+
+- [ ] AgendaView
+- [ ] EventPopover
 - [ ] AttendeeList
+
+## T30d Calendar · Editing
+
+- [ ] EventEditor
+- [ ] RecurrenceEditor
+- [ ] ReminderPicker
+- [ ] AvailabilityPicker