Add agent components 451-465 and icon.Crystal

Fifteen components that dress an AI agent's work as an RPG party:
AgentCard, ToolCall, PlanQuest, ThinkingOrb, TokenMana, ApprovalPrompt,
AgentLog, SubAgentParty, MemoryCrystals, AgentStatus, DiffScroll,
ModelSelect, PromptBox, CostCoins and Checkpoints.

The context window is HP and the token budget MP; tool calls are spells
that CAST, glow, then land OK or FAILED; the transcript reads as a battle
log whose newest line types itself out; models line up like fighters.
Busy signs keep moving under Reduce Motion, decoration stops. Commands
and prompts never reach the log, and a veiled PromptBox casts nothing.

icon.Crystal is the new 12x12 save and memory crystal.

agent/agentlog.go

@@ -0,0 +1,102 @@
+package agent
+
+import (
+	"fmt"
+	"math"
+	"unicode/utf8"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/layout"
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+// Kind is what a log step did.
+type Kind int
+
+const (
+	Thought Kind = iota
+	Cast
+	Hit
+	Miss
+	Said
+)
+
+var kinds = [...]struct {
+	msg  string
+	slot pixel.Slot
+}{{"log_thought", pixel.Faint}, {"log_cast", pixel.Info}, {"log_hit", pixel.Good}, {"log_miss", pixel.Bad}, {"log_said", pixel.Ink}}
+
+// LogStep is a line of the transcript.
+type LogStep struct {
+	Kind Kind
+	Text string
+}
+
+type AgentLogOptions struct {
+	// Width and Height are dots; zeros mean 240 by 120.
+	Width, Height int
+}
+
+type agentLogKey struct{}
+
+// AgentLog tells steps as a battle log, the newest typed.
+func AgentLog(c *ui.Context, text, agent string, steps []LogStep, o AgentLogOptions) *ui.Element {
+	k := pixel.K(c)
+	if agent == "" {
+		panic("agent: AgentLog has no agent")
+	}
+	lines := make([]string, len(steps))
+	for i, s := range steps {
+		if s.Kind < Thought || s.Kind > Said || s.Text == "" {
+			panic(fmt.Sprintf("agent: AgentLog step %d is kind %d with %q", i, s.Kind, s.Text))
+		}
+		// Hits and misses tell the outcome, not who.
+		args := []any{agent, s.Text}
+		if s.Kind == Hit || s.Kind == Miss {
+			args = args[1:]
+		}
+		lines[i] = fmt.Sprintf(k.Msg(kinds[s.Kind].msg), args...)
+	}
+	w, h := pixel.Or("AgentLog Width", o.Width, 240), pixel.Or("AgentLog Height", o.Height, 120)
+	box := ui.Box(c).Size(k.D(w), k.D(h))
+	s := ui.Local(box, agentLogKey{}, func() ui.ScrollState { return ui.ScrollState{} })
+	return box.Children(func() {
+		layout.ScrollArea(c, s, layout.ScrollAreaOptions{Label: text, Follow: true}, func() {
+			col := ui.Column(c).FillWidth().Padding(k.D(4)).Gap(k.D(2))
+			// A new line types out, three glyphs a step.
+			newest := 0
+			if len(lines) > 0 {
+				newest = utf8.RuneCountInString(lines[len(lines)-1])
+			}
+			shown := 3 * k.Shot(c, col, len(steps), 15, (newest+2)/3)
+			col.Children(func() {
+				for i, l := range lines {
+					n := math.MaxInt
+					if i == len(lines)-1 {
+						n = shown
+					}
+					typed(c, k, l, kinds[steps[i].Kind].slot, n)
+				}
+			})
+		}).Element.Fill()
+	})
+}
+
+// typed draws s wrapped, but only its first n glyphs.
+func typed(c *ui.Context, k pixel.Kit, s string, ink pixel.Slot, n int) {
+	e := ui.Box(c).FillWidth().Role(ui.RoleText).Label(s)
+	width, check := pixel.WrapWidth(c, e)
+	lines := pixel.Wrap(s, width, 0)
+	e.Height(k.D(len(lines) * pixel.LineHeight)).Draw(func(p *ui.Painter, r ui.Rect) {
+		check(r)
+		g, left := k.Canvas(p, r), n
+		for i, l := range lines {
+			rs := []rune(l)
+			g.Text(0, i*pixel.LineHeight, string(rs[:min(left, len(rs))]), ink, 1)
+			if left -= len(rs); left <= 0 {
+				return
+			}
+		}
+	})
+}