Add datetime components 196-215; Kit.At; inert stepper arrows

Calendars, date and time inputs, pickers, clocks, timers, a sun dial,
a season wheel, an agenda and a day schedule. Kit.At rebuilds at a
moment (relative times, midnight). Stepper and NumberInput arrows stop
under Inert. DateInput parks a popup focus as its own.

datetime/log_test.go

@@ -0,0 +1,53 @@
+package datetime_test
+
+import (
+	"bytes"
+	"log/slog"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/datetime"
+)
+
+func TestPopupsAndPagesAreLogged(t *testing.T) {
+	var buf bytes.Buffer
+	old := slog.Default()
+	slog.SetDefault(slog.New(slog.NewTextHandler(&buf, &slog.HandlerOptions{Level: slog.LevelDebug})))
+	defer slog.SetDefault(old)
+	date, month, year := raid, raid, 2026
+	tt := view(600, 500, newClock(), false, func(c *ui.Context) {
+		ui.Row(c).Gap(8).Children(func() {
+			datetime.DateInput(c, "Due", &date, datetime.DateInputOptions{})
+			datetime.MonthPicker(c, "Month", &month, datetime.MonthPickerOptions{})
+			datetime.YearPicker(c, "Year", &year, datetime.YearPickerOptions{})
+		})
+	})
+	click(t, tt, "Due")
+	tt.Key(0, ui.KeyEscape)
+	for _, l := range []string{"Month", "Year"} {
+		r := find(t, tt, l)
+		tt.ClickAt(r.X+16, r.Y-20)
+	}
+	out := buf.String()
+	for _, want := range []string{"date input popup", "month picker turned", "year picker turned"} {
+		if !strings.Contains(out, want) {
+			t.Errorf("no %q in the logs:\n%s", want, out)
+		}
+	}
+}
+
+func TestInertTimerKeepsItsSetting(t *testing.T) {
+	set := time.Minute
+	tt := view(400, 200, newClock(), true, func(c *ui.Context) {
+		datetime.Timer(c, "Egg", &set, datetime.TimerOptions{})
+	})
+	r := find(t, tt, "MIN")
+	tt.Press(r.X+r.W+12, r.Y+8)
+	tt.Release(r.X+r.W+12, r.Y+8)
+	if set != time.Minute {
+		t.Fatalf("an inert timer was set to %v", set)
+	}
+}