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/nook/changelog.tsx

@@ -0,0 +1,81 @@
+/**
+ * `/changelog` on the Nook subdomain — rendered from the Sparkle appcast.
+ *
+ * The appcast already ships HTML release notes to the updater on every
+ * launch, so this page renders exactly what Sparkle publishes: one source
+ * of truth, no second place to write release notes. Doubles as the raw
+ * material for the release-announcement job (marketing/README.md).
+ */
+import { For, Show } from "solid-js";
+import { query, createAsync } from "@solidjs/router";
+import { PageHead } from "~/components/PageHead";
+import { EdgeCacheHeaders } from "~/components/EdgeCacheHeaders";
+import SubdomainHeader from "~/components/SubdomainHeader";
+import { fetchAppcastReleases } from "~/routes/api/the-nook/_appcast";
+
+const getReleases = query(async () => {
+  "use server";
+  return fetchAppcastReleases();
+}, "nook-changelog-releases");
+
+export default function NookChangelogPage() {
+  const releases = createAsync(() => getReleases());
+
+  return (
+    <>
+      <EdgeCacheHeaders maxAge={300} />
+      <PageHead
+        title="Changelog"
+        description="Every release of The Nook, newest first — agent orchestration, fan and thermal control for macOS."
+        ogTitle="The Nook changelog"
+      />
+      <SubdomainHeader />
+      <main class="min-h-screen px-[8vw] py-[8vh]">
+        <h1 class="text-text mb-3 text-3xl font-bold tracking-tight sm:text-4xl">
+          Changelog
+        </h1>
+        <p class="text-subtext0 mb-10 max-w-2xl text-lg">
+          What changed in each release. The app updates through Sparkle —
+          every entry here is what the updater shows.
+        </p>
+
+        <Show
+          when={(releases()?.length ?? 0) > 0}
+          fallback={
+            <p class="text-subtext0 text-sm">
+              No releases published yet — check back soon.
+            </p>
+          }
+        >
+          <div class="border-overlay0 space-y-10 border-l pl-6">
+            <For each={releases()}>
+              {(release) => (
+                <article>
+                  <div class="mb-2 flex flex-wrap items-baseline gap-x-3 gap-y-1">
+                    <h2 class="text-text text-xl font-semibold">
+                      Version {release.version}
+                    </h2>
+                    <Show when={release.build}>
+                      <span class="text-subtext1 font-mono text-xs">
+                        build {release.build}
+                      </span>
+                    </Show>
+                    <Show when={release.date}>
+                      <span class="text-subtext1 text-xs">{release.date}</span>
+                    </Show>
+                  </div>
+                  {/* Notes are the publisher's own HTML, written to the same
+                      S3 appcast the Sparkle updater consumes. */}
+                  <div
+                    class="text-subtext0 text-sm [&_h2]:mt-3 [&_h2]:mb-1 [&_h2]:text-base [&_h2]:font-semibold [&_h2]:text-text [&_li]:ml-5 [&_li]:list-disc [&_p]:mb-2 [&_ul]:mb-2"
+                    innerHTML={release.notesHtml}
+                  />
+                </article>
+              )}
+            </For>
+          </div>
+        </Show>
+      </main>
+    </>
+  );
+}