Add chat components 321-345; named List rows, inert scroll views

Speech bubbles, a chat log that follows its end, a composer that sends
on Enter, typing dots, chat and channel lists, read receipts,
reactions, emoji and sticker pickers, mentions, date and unread rules,
system lines, member lists, user cards, a mailbox, mail reader and
letter, a notification bell, call controls, a voice meter, attachment
chips, link previews and polls.

pixel's editor takes EnterSends; display's Bubble takes a Fill and
exports EmojiSprite. data.List names its rows, which also lets typing
choose one. layout.ScrollArea and input.TextArea hold still under
Inert, and an inert scroll view leaves the Tab order until it wakes.

chat/speechbubble.go

@@ -0,0 +1,32 @@
+package chat
+
+import (
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/display"
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/text"
+)
+
+type SpeechBubbleOptions struct {
+	// Width wraps the text; zero means 140.
+	Width int
+}
+
+// SpeechBubble shows who said what, when; tail their side.
+func SpeechBubble(c *ui.Context, m Message, o SpeechBubbleOptions) *ui.Element {
+	k := pixel.K(c)
+	w := pixel.Or("SpeechBubble Width", o.Width, 140)
+	// Yours sit right on Accent, written in AccentInk.
+	side, tail, fill, ink := ui.Start, display.Left, pixel.Lit, pixel.Ink
+	if m.Mine {
+		side, tail, fill, ink = ui.End, display.Right, pixel.Accent, pixel.AccentInk
+	}
+	return ui.Column(c).AlignSelf(side).AlignItems(side).Gap(k.D(1)).Children(func() {
+		pixel.Text(c, line(m.From, w), pixel.TextOptions{Slot: pixel.Faint})
+		display.Bubble(c, display.BubbleOptions{Tail: tail, At: 4, Fill: fill}, func() {
+			para(c, k, m.Text, w, 0, ink)
+		})
+		text.MicroText(c, clock(m.At), text.MicroTextOptions{Slot: pixel.Faint})
+	})
+}