feat: add GitHub star nudges to CLI build view and docs sidebar (#271)

* feat: load star count during context builds

* docs: document star prompt opt-out

* fix: initialize demo context star count

* feat(docs-site): add GitHub star count widget to docs sidebar

* test: isolate star-prompt build-view tests from ambient CI env

docs-site/components/github-stars.tsx

@@ -0,0 +1,93 @@
+import { Suspense } from "react";
+import { GitHubIcon } from "@/components/github-icon";
+
+const REPO = "kaelio/ktx";
+const REPO_URL = `https://github.com/${REPO}`;
+const API_URL = `https://api.github.com/repos/${REPO}`;
+
+async function fetchStarCount(): Promise<number | null> {
+  try {
+    const res = await fetch(API_URL, {
+      headers: { Accept: "application/vnd.github+json" },
+      // Revalidate hourly. GitHub's unauthenticated REST limit is 60 req/h per
+      // IP, so a single cached server-side fetch keeps the count fresh while
+      // never exposing visitors to rate limits or layout shift.
+      next: { revalidate: 3600 },
+    });
+    if (!res.ok) return null;
+    const data = (await res.json()) as { stargazers_count?: unknown };
+    return typeof data.stargazers_count === "number"
+      ? data.stargazers_count
+      : null;
+  } catch {
+    return null;
+  }
+}
+
+/** Compact, GitHub-style count: 847 → "847", 1234 → "1.2k", 12345 → "12.3k". */
+function formatStars(count: number): string {
+  if (count < 1000) return count.toLocaleString("en-US");
+  const thousands = count / 1000;
+  const rounded =
+    thousands >= 100 ? Math.round(thousands) : Math.round(thousands * 10) / 10;
+  return `${rounded}k`;
+}
+
+function StarGlyph() {
+  return (
+    <svg className="ktx-stars-star" viewBox="0 0 24 24" aria-hidden="true">
+      <path d="M12 2.6l2.9 5.88 6.49.95-4.7 4.57 1.11 6.46L12 17.4l-5.8 3.06 1.11-6.46-4.7-4.57 6.49-.95z" />
+    </svg>
+  );
+}
+
+async function StarsContent() {
+  const count = await fetchStarCount();
+  const label =
+    count === null
+      ? "Star ktx on GitHub"
+      : `Star ktx on GitHub — ${count.toLocaleString("en-US")} stars`;
+
+  return (
+    <a
+      href={REPO_URL}
+      target="_blank"
+      rel="noopener noreferrer"
+      aria-label={label}
+      className="ktx-stars"
+    >
+      <span className="ktx-stars-seg ktx-stars-seg--label">
+        <GitHubIcon className="ktx-stars-gh" />
+        <span className="ktx-stars-text">Star</span>
+      </span>
+      {count !== null && (
+        <span className="ktx-stars-seg ktx-stars-seg--count">
+          <StarGlyph />
+          <span className="ktx-stars-count">{formatStars(count)}</span>
+        </span>
+      )}
+    </a>
+  );
+}
+
+function StarsSkeleton() {
+  return (
+    <span className="ktx-stars ktx-stars--skeleton" aria-hidden="true">
+      <span className="ktx-stars-seg ktx-stars-seg--label">
+        <GitHubIcon className="ktx-stars-gh" />
+        <span className="ktx-stars-text">Star</span>
+      </span>
+      <span className="ktx-stars-seg ktx-stars-seg--count">
+        <span className="ktx-stars-skeleton-bar" />
+      </span>
+    </span>
+  );
+}
+
+export function GitHubStars() {
+  return (
+    <Suspense fallback={<StarsSkeleton />}>
+      <StarsContent />
+    </Suspense>
+  );
+}