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.md

@@ -106,8 +106,11 @@ Per-component lines live in `tasks/`. Tags there:
 - [x] T29a Mail · Boxes and lists
 - [x] T29b Mail · Reading
 - [x] T29c Mail · Writing
-- [ ] T29d Mail · Sorting
-- [ ] T30 Calendar
+- [x] T29d Mail · Sorting
+- [ ] T30a Calendar · Months
+- [ ] T30b Calendar · Time grid
+- [ ] T30c Calendar · Agenda and people
+- [ ] T30d Calendar · Editing
 - [ ] T31 Project — `tasks/ch31-43.md`
 - [ ] T32 Canvas & Design
 - [ ] T33 DB & Dev Tools
@@ -350,3 +353,4 @@ Per-component lines live in `tasks/`. Tags there:
 | T29c | 2 | PASS | |
 | T29d | 1 | FAIL | the time dialog's rule for a time ahead of now had no test; its test found that a picker opened in a dialog panicked on a deferred draw inside another |
 | T29d | 2 | FAIL | a raise inside a raise took its place in the queue as its namespace, so one appearing before it rebuilt its state and dropped its focus |
+| T29d | 3 | PASS | |