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/memorycrystals.go

@@ -0,0 +1,90 @@
+package agent
+
+import (
+	"fmt"
+	"log/slog"
+	"slices"
+
+	"github.com/egoist/mygo/ui"
+
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/icon"
+	"git.zacharyzhang.com/ZacharyZhang-NY/8bitMyGoUI/pixel"
+)
+
+type MemoryCrystalsOptions struct {
+	// Slots is how many crystals; zero means 8.
+	Slots    int
+	Disabled bool
+}
+
+type MemoryCrystalsResult struct {
+	Element *ui.Element
+	// Picked is the crystal chosen this frame, else -1.
+	Picked int
+}
+
+var (
+	twinkle = pixel.MustSprite(`
+		..#..
+		..#..
+		##.##
+		..#..
+		..#..`)
+)
+
+type crystalKey struct{}
+
+const crystalW, crystalH = 26, 30
+
+// MemoryCrystals keeps memories in crystals; empty ones stay dark.
+func MemoryCrystals(c *ui.Context, text string, memories []string, o MemoryCrystalsOptions) MemoryCrystalsResult {
+	k := pixel.K(c)
+	n := pixel.Or("MemoryCrystals Slots", o.Slots, 8)
+	if len(memories) > n || slices.Contains(memories, "") {
+		panic(fmt.Sprintf("agent: MemoryCrystals has %d memories for %d slots, or a blank", len(memories), n))
+	}
+	cols := min(n, 8)
+	col := ui.Column(c).Gap(k.D(4))
+	cur := ui.Local(col, crystalKey{}, func() int { return 0 })
+	*cur = min(*cur, n-1)
+	res := MemoryCrystalsResult{Picked: -1}
+	res.Element = col.Children(func() {
+		shell, base, st, picked := pixel.Pad(c, text, cols, n, crystalW, crystalH, cur, o.Disabled)
+		res.Picked = picked
+		at, held := *cur, len(memories)
+		line, ink := fmt.Sprintf("%d/%d: %s", at+1, n, k.Msg("empty_crystal")), pixel.Faint
+		if at < held {
+			line, ink = fmt.Sprintf("%d/%d: %s", at+1, n, memories[at]), pixel.Ink
+		}
+		base.Description(line)
+		shell.Draw(func(p *ui.Painter, r ui.Rect) {
+			g := k.Canvas(p, r)
+			if st.Focus {
+				g.Cursor(at%cols*crystalW, at/cols*crystalH, crystalW, crystalH)
+			}
+			// Held crystals twinkle in turn; Reduce Motion stills them.
+			step := g.Step(4)
+			for i := range n {
+				x, y := i%cols*crystalW, i/cols*crystalH
+				if i >= held {
+					g.Sprite(x+1, y+3, icon.Crystal, 0, pixel.Well, 2)
+					continue
+				}
+				g.Sprite(x+1, y+3, icon.Crystal, 0, pixel.Magic, 2)
+				if (step+i*3)%8 == 0 {
+					g.Sprite(x+15, y+5, twinkle, 0, pixel.Lit, 1)
+				}
+			}
+			g.Finish(st)
+		})
+		ui.Box(c).Size(k.D(cols*crystalW), k.D(pixel.LineHeight+6)).Role(ui.RoleNone).Draw(func(p *ui.Painter, r ui.Rect) {
+			g := k.Canvas(p, r)
+			g.Frame(0, 0, g.W, g.H, pixel.Sunken, pixel.Well)
+			g.Text(4, 3, pixel.Wrap(line, g.W-8, 1)[0], ink, 1)
+		})
+	})
+	if res.Picked >= 0 {
+		slog.Debug("8bit: memory crystal picked", "label", text, "slot", res.Picked)
+	}
+	return res
+}