Add account components 386-405; Reduce setting, PinInput Cmd+V

Twenty account components: SettingsList, OptionCycler, KeyBindings,
ControllerMap, ProfileCard, CharacterCreator, LoginForm, PasswordGrid,
SessionList, LanguagePicker, PalettePicker, VolumeMixer,
DifficultySelect, AccessibilityOptions, AccountSwitcher, PlayerSelect,
TwoFactor, About, PatchNotes and FeedbackForm.

The components never check credentials, and no secret reaches the log:
LoginForm reports Submitted and the caller counts Failures; each new
failure clears the password, refocuses it, shakes the form and names no
field. TwoFactor builds on input.PinInput and drains an epoch-aligned
period bar. PalettePicker draws each tile in its own palette on a
pixel.Pad grid.

pixel.Settings.Reduce stills motion like the system preference, the
micro font gains '?', display.Face draws avatar faces anywhere, and
input.PinInput pastes on Cmd+V as native hosts send it.

account/twofactor.go

@@ -0,0 +1,74 @@
+package account
+
+import (
+	"fmt"
+	"log/slog"
+	"strings"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/input"
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type TwoFactorOptions struct {
+	// Period is a code's life; zero means 30 s.
+	Period   time.Duration
+	Disabled bool
+}
+
+type TwoFactorResult struct {
+	Element *ui.Element
+	// Submitted is the sixth box filled.
+	Changed, Submitted bool
+}
+
+// TwoFactor takes a six-digit code; a bar drains its period.
+func TwoFactor(c *ui.Context, text string, code *string, o TwoFactorOptions) TwoFactorResult {
+	k := pixel.K(c)
+	period := o.Period
+	if period == 0 {
+		period = 30 * time.Second
+	}
+	if period < time.Second || len(*code) > 6 || strings.Trim(*code, "0123456789") != "" {
+		panic(fmt.Sprintf("account: TwoFactor code of %d runes, period %v", len(*code), period))
+	}
+	var res TwoFactorResult
+	// The bar spans the boxes, not the parent.
+	res.Element = ui.Column(c).AlignSelf(ui.Start).Gap(k.D(4)).Children(func() {
+		// PinInput takes typing, paste and Backspace.
+		pin := input.PinInput(c, text, code, input.PinInputOptions{Length: 6, Disabled: o.Disabled})
+		res.Changed, res.Submitted = pin.Changed, pin.Complete
+		now := k.Now()
+		k.At(c, now.Truncate(time.Second).Add(time.Second))
+		secs := secondsLeft(now, period)
+		ui.Box(c).FillWidth().Height(k.D(6)).Role(ui.RoleProgress).Label(k.Msg("time_left")).Description(fmt.Sprintf("%d s", secs)).Draw(func(p *ui.Painter, r ui.Rect) {
+			g := k.Canvas(p, r)
+			// The bar drains on 4 fps steps of the clock.
+			rest := period - time.Duration(g.Busy(4))*(time.Second/4)%period
+			bar := pixel.Good
+			switch {
+			case rest <= 5*time.Second:
+				bar = pixel.Bad
+			case rest <= 10*time.Second:
+				bar = pixel.Warn
+			}
+			g.Frame(0, 0, g.W, 6, pixel.Sunken, pixel.Well)
+			// Floats, so long periods cannot overflow.
+			g.Rect(2, 2, int(float64(g.W-4)*float64(rest)/float64(period)), 2, bar)
+		})
+	})
+	// The code never reaches the log, only its length.
+	if res.Changed {
+		slog.Debug("8bit: two factor", "label", text, "length", len(*code), "submitted", res.Submitted)
+	}
+	return res
+}
+
+// secondsLeft rounds up the time left in now's period, epoch-aligned.
+func secondsLeft(now time.Time, period time.Duration) int64 {
+	left := period - time.Duration(now.UnixNano()%int64(period))
+	// left is at least 1 ns; this form cannot overflow.
+	return int64(1 + (left-1)/time.Second)
+}