nook: list Muse on the agents page

nook.freno.me/agents listed twelve agents and said "twelve" in its meta
description, OG title and intro, while the app's registry (AgentSpec.all)
gained Muse in 0.10.0 as its thirteenth. The page mirrors that registry
by hand from another repo, so nothing flagged the drift.

Adds the Muse card from its plugin manifest and registry row: the plugin
body at ~/.nook/plugins/muse installed through Muse's own plugins CLI,
its fourteen hook events, approvals answerable from a card (every tool
call under Verify), and this Mac only since remote hosts skip it. The
positioning claims table and copy move to thirteen with it.

Tests: src/routes/nook/agents.test.ts pins the roster to the registry's
names in order (red on master: Muse missing) and every stated count to
the number of entries (red when the intro says twelve again).

NOOK-336

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/routes/nook/agents.test.ts

@@ -0,0 +1,54 @@
+/**
+ * Regression test for the /agents roster (NOOK-336).
+ *
+ * The page mirrors the app's registry, `AgentSpec.all` in
+ * the-nook/Sources/NookCore/Agents/AgentRegistry.swift. When Muse joined
+ * the registry in 0.10.0 the page kept twelve entries and kept saying
+ * "twelve", so a shipped agent was missing from the one page that lists
+ * them. The registry lives in another repo, so the expected roster is
+ * restated here; when an agent is added there, add it here and on the page.
+ *
+ * STATIC SOURCE AUDIT, the same pattern as the downloads regressions.
+ */
+import { describe, it, expect } from "bun:test";
+import { readFileSync } from "node:fs";
+import { join } from "node:path";
+
+const SOURCE = readFileSync(join(import.meta.dir, "agents.tsx"), "utf8");
+
+/** AgentSpec.all display names, in registry order. */
+const REGISTRY = [
+  "Claude Code",
+  "Codex",
+  "OpenCode",
+  "Pi",
+  "Oh My Pi",
+  "Muse",
+  "Hermes",
+  "OpenClaw",
+  "Z.ai (ZCode)",
+  "Gemini CLI",
+  "Cline",
+  "Qwen Code",
+  "DeepSeek"
+];
+
+const NUMBER_WORDS = ["twelve", "thirteen", "fourteen", "fifteen"];
+
+const entries = [...SOURCE.matchAll(/^\s{4}name: "([^"]+)",$/gm)].map((m) => m[1]);
+
+describe("Nook /agents roster (NOOK-336)", () => {
+  it("lists every registry agent, in registry order", () => {
+    expect(entries).toEqual(REGISTRY);
+  });
+
+  it("states the same count everywhere it names one", () => {
+    const word = NUMBER_WORDS[entries.length - 12];
+    for (const other of NUMBER_WORDS.filter((w) => w !== word)) {
+      expect(SOURCE.toLowerCase()).not.toContain(other);
+    }
+    expect(SOURCE).toContain(`all ${word}`);
+    expect(SOURCE).toContain(`The ${entries.length} agents`);
+    expect(SOURCE).toContain(`watches ${word} coding agents`);
+  });
+});