Add fx components 291-320 and the home scene; Kit.Shot, Kit.Toward

Palette cycling, sky, sun and moon, clouds, starfield, rain, snow,
petals, leaves, fireflies, waterfall, ocean, campfire, lava, aurora,
lightning, mountains and a season scene; scanlines, vignette, screen
shake, flash, dither fades, iris wipes, dissolves, mosaics, glitches,
sparkles, explosions and confetti. Home opens on a live scene in the
palette's season and a strip of all eight palettes.

pixel adds Canvas.Cycled, Sprite.At, SpriteOf, Kit.Toward and
Kit.Shot, which spends a cue under Reduce Motion so it never replays;
display exports Reduce. Gallery grids and the sidebar are one Tab
stop each.

overlay/overlay.go

@@ -128,8 +128,5 @@ func arriving(c *ui.Context, home *ui.Element, open bool) int {
 	if open {
 		on = 1
 	}
-	if k.Reduce() {
-		return 0
-	}
-	return 4 - k.Since(c, k.Cue(home, on), 15, 4)
+	return 4 - k.Shot(c, home, on, 15, 4)
 }