Add media components 346-365; input.SlideBase, guarded Pad

An audio player with transport, scrubber and volume; an equalizer and
a visualizer; a playlist; a cassette, cartridge and record that turn
while they play and hold where they stop; piano keys, a step sequencer
and a tracker you can type into; a waveform, a 16:9 video frame, an
image compare, a gallery, a filmstrip, a record button and an FM tuner.

input exports SlideBase, the undrawn rail its sliders share; the
gallery treats exported Bases as building blocks, not components.
pixel's micro font gains '#' for notes like C#4. pixel.Pad and the
slide rail read input only while their base is enabled, so Inert or a
fresh Disabled stops a drag or a key already sent. AGENTS records why
a drawn container keeps the DISABLED description: MyGo paints a
disabled subtree at half opacity.

media/recordbutton.go

@@ -0,0 +1,80 @@
+package media
+
+import (
+	"log/slog"
+	"time"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/input"
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type RecordButtonOptions struct {
+	Disabled bool
+}
+
+type RecordButtonResult struct {
+	Element *ui.Element
+	Changed bool
+}
+
+type takeKey struct{}
+
+// take is when recording began and the last take's length.
+type take struct {
+	since time.Time
+	took  time.Duration
+}
+
+var (
+	recDot = pixel.MustSprite(`
+		..rrr..
+		.rrrrr.
+		rrrrrrr
+		rrrrrrr
+		rrrrrrr
+		.rrrrr.
+		..rrr..
+	`)
+	recOff = pixel.MustSprite(`
+		..sss..
+		.s...s.
+		s.....s
+		s.....s
+		s.....s
+		.s...s.
+		..sss..
+	`)
+)
+
+// RecordButton toggles *rec; the dot blinks, time runs.
+func RecordButton(c *ui.Context, text string, rec *bool, o RecordButtonOptions) RecordButtonResult {
+	k := pixel.K(c)
+	now := k.Now()
+	row := ui.Row(c)
+	tk := ui.Local(row, takeKey{}, func() take { return take{} })
+	// Follow *rec, whoever flips it; a click builds again.
+	switch {
+	case *rec && tk.since.IsZero():
+		tk.since, tk.took = now, 0
+	case !*rec && !tk.since.IsZero():
+		tk.since, tk.took = time.Time{}, now.Sub(tk.since)
+	}
+	took, dot := tk.took, recDot
+	if *rec {
+		took = now.Sub(tk.since)
+		k.At(c, tk.since.Add(took.Truncate(time.Second)+time.Second))
+		if !k.Reduce() && k.Tick(c, 2)%2 == 1 {
+			dot = recOff
+		}
+	}
+	res := RecordButtonResult{Element: row}
+	row.Children(func() {
+		res.Changed = input.Toggle(c, k.Msg("rec")+" "+mmss(took), rec, input.ToggleOptions{Icon: dot, Label: text + ", " + mmss(took), Disabled: o.Disabled}).Changed
+	})
+	if res.Changed {
+		slog.Debug("8bit: record button", "label", text, "rec", *rec, "time", mmss(took))
+	}
+	return res
+}