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.

gallery/agent_demo_test.go

@@ -0,0 +1,43 @@
+package gallery
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestAgentDemosLogTheirActions(t *testing.T) {
+	// Clicks that only focus a component may log nothing.
+	quiet := map[string]bool{"Prompt": true}
+	for _, tc := range []struct {
+		path  string
+		steps []string
+	}{
+		{"/c/451-agentcard", []string{"READ A BIG FILE", "COMPACT"}}, {"/c/452-toolcall", []string{"CAST GREP"}},
+		{"/c/453-planquest", []string{"COMPLETE STEP"}}, {"/c/454-thinkingorb", []string{"PONDER"}},
+		{"/c/455-tokenmana", []string{"CAST (12K)", "DRINK ETHER"}}, {"/c/456-approvalprompt", []string{"YES", "NO"}},
+		{"/c/457-agentlog", []string{"NEXT STEP"}}, {"/c/458-subagentparty", []string{"SUMMON", "NEXT TURN"}},
+		{"/c/459-memorycrystals", []string{"Memories"}}, {"/c/462-modelselect", []string{"Models"}},
+		{"/c/463-promptbox", []string{"Prompt", "type:ship it", "key:Enter"}}, {"/c/464-costcoins", []string{"RUN THE AGENT", "NEW MONTH"}},
+		{"/c/465-checkpoints", []string{"RESTORE Tests green", "SAVE HERE"}},
+	} {
+		a, tt := open(tc.path)
+		slug := tc.path[3:]
+		for _, step := range tc.steps {
+			before := len(a.logs[slug])
+			if k, ok := strings.CutPrefix(step, "key:"); ok {
+				tt.Key(0, letters[k])
+			} else if s, ok := strings.CutPrefix(step, "type:"); ok {
+				tt.Type(s)
+			} else {
+				click(t, tt, step)
+			}
+			if len(a.logs[slug]) <= before && !quiet[step] {
+				t.Errorf("%s: %s logged nothing: %q", slug, step, a.logs[slug])
+			}
+		}
+		// A prompt may hold secrets: the log counts, never quotes.
+		if strings.Contains(strings.Join(a.logs[slug], " "), "ship it") {
+			t.Errorf("%s logged the prompt: %q", slug, a.logs[slug])
+		}
+	}
+}