nook: add /agents, /changelog and /faq

Three organic surfaces, each answering an objection at the moment it
bites. /agents lists all twelve agents with each hook's exact event
surface (mirrors AgentSpec.all + hook/setup.go + the plugins) and what
a card can do — allow/deny or observe. /changelog renders the appcast
HTML the Sparkle updater already publishes, so release notes have one
source of truth. /faq answers privacy (scoped honestly: no prompt or
code content leaves the device), the notch question, battery,
permissions, the macOS 14 floor and offline use — no refund question,
per decision: the trial is the answer. Nav gains the three links.

Tests: appcast parser suite (5 tests) covers CDATA, escaped HTML,
Version-prefix titles and garbage input.

Issues: FRE-12, FRE-13, FRE-14

src/routes/api/the-nook/appcast.test.ts

@@ -0,0 +1,64 @@
+import { describe, expect, it } from "bun:test";
+import { parseAppcastItems } from "./_appcast";
+
+// The /changelog page renders exactly what the Sparkle updater receives, so
+// the parser's contract is the appcast's contract: newest-first items, a
+// shortVersionString title with the raw <title> as fallback, CDATA and
+// plain-encoded descriptions both accepted, garbage in → empty list out.
+
+const item = (over: Record<string, string>) => `
+  <item>
+    <title>Version ${over.title ?? "1.0.0"}</title>
+    ${over.short ? `<sparkle:shortVersionString>${over.short}</sparkle:shortVersionString>` : ""}
+    ${over.build ? `<sparkle:version>${over.build}</sparkle:version>` : ""}
+    ${over.date ? `<pubDate>${over.date}</pubDate>` : ""}
+    ${over.desc ?? `<description><![CDATA[<ul><li>Fixes</li></ul>]]></description>`}
+    <enclosure url="https://example.com/Nook-1.0.0.dmg" type="application/x-apple-diskimage"/>
+  </item>`;
+
+describe("parseAppcastItems", () => {
+  it("parses newest-first items with version, build, date and CDATA notes", () => {
+    const xml = `<rss><channel>
+      ${item({ title: "1.2.0", short: "1.2.0", build: "42", date: "Sat, 03 Oct 2026 12:00:00 +0000" })}
+      ${item({ title: "1.1.0", short: "1.1.0", build: "41", date: "Fri, 02 Oct 2026 12:00:00 +0000" })}
+    </channel></rss>`;
+
+    const releases = parseAppcastItems(xml);
+    expect(releases.length).toBe(2);
+    expect(releases[0].version).toBe("1.2.0");
+    expect(releases[0].build).toBe("42");
+    expect(releases[0].date).toContain("03 Oct 2026");
+    expect(releases[0].notesHtml).toBe("<ul><li>Fixes</li></ul>");
+    expect(releases[1].version).toBe("1.1.0");
+  });
+
+  it("falls back to the plain title when shortVersionString is absent", () => {
+    const xml = `<rss><channel>${item({ title: "1.0.0" })}</channel></rss>`;
+    const releases = parseAppcastItems(xml);
+    expect(releases[0].version).toBe("1.0.0");
+    expect(releases[0].build).toBeNull();
+  });
+
+  it("accepts non-CDATA escaped-HTML descriptions", () => {
+    const xml = `<rss><channel>
+      ${item({ desc: "<description>&lt;p&gt;Hello&lt;/p&gt;</description>" })}
+    </channel></rss>`;
+    expect(parseAppcastItems(xml)[0].notesHtml).toBe("<p>Hello</p>");
+  });
+
+  it("returns [] for empty, non-XML, or item-less input", () => {
+    expect(parseAppcastItems("")).toEqual([]);
+    expect(parseAppcastItems("<html>not an appcast</html>")).toEqual([]);
+    expect(parseAppcastItems("<rss><channel></channel></rss>")).toEqual([]);
+  });
+
+  it("skips items with no version signal at all", () => {
+    const xml = `<rss><channel>
+      <item><description><![CDATA[<p>orphan</p>]]></description></item>
+      ${item({ title: "1.0.0" })}
+    </channel></rss>`;
+    const releases = parseAppcastItems(xml);
+    expect(releases.length).toBe(1);
+    expect(releases[0].version).toBe("1.0.0");
+  });
+});