docs: consolidate AI Resources into a single page (#274)

* docs: consolidate AI Resources into a single page

The AI Resources section was four pages (agent-quickstart, markdown-access,
agent-instructions, prompt-recipes) that repeated the same docs-consumption
guidance. Collapse them into one page at /docs/ai-resources covering markdown
endpoints, retrieval order, the task router, agent instructions, prompts, and
guardrails.

Also fix a stale claim: the page actions are a single "Copy as Markdown"
button, not the documented "Copy MD / View MD / Copy MDX" trio.

Update the cross-references in README, the introduction cards, the quickstart,
and the llms.txt entry points to the consolidated page.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* fix(docs-site): redirect retired AI Resources slugs, preserving .md route

Redirect the retired per-page slugs (/docs/ai-resources/*) to the consolidated
page. Because Next evaluates redirects before the .md rewrite, a single
catch-all would 308 a cached per-page Markdown URL to the HTML page and break
the agent Markdown contract. Match the .md variant first and keep its suffix so
it lands on /docs/ai-resources.md.

Extend the routing test to assert both the HTML and .md redirects, and that
following the .md URL end to end serves text/markdown.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* docs: move AI Resources under the Community & Resources section

As a single page, AI Resources rendered as an orphaned, unbolded link wedged
between the top-level multi-page sections instead of as a section of its own.
Move it under Community (renamed "Community & Resources") so it renders as a
normal child link, consistent with how the single-page Configuration section
already works.

Redirect the former top-level URL and the retired per-page slugs (HTML and .md,
the .md variants first so cached Markdown URLs keep their suffix) to the new
home, relabel the llms.txt group to match, and repoint the README, introduction,
quickstart, and llms.txt cross-links.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

docs-site/tests/docs-index-route.test.mjs

@@ -145,6 +145,53 @@ test("/ktx/docs redirects to the docs introduction", async () => {
   );
 });
 
+test("retired AI Resources URLs redirect to the page under Community", async () => {
+  // The former top-level URL.
+  const bare = await fetch(
+    `${docsSiteUrl}${docsBasePath}/docs/ai-resources`,
+    { redirect: "manual" },
+  );
+
+  assert.equal(bare.status, 308);
+  assert.equal(
+    bare.headers.get("location"),
+    `${docsBasePath}/docs/community/ai-resources`,
+  );
+
+  // A retired per-page slug.
+  const slug = await fetch(
+    `${docsSiteUrl}${docsBasePath}/docs/ai-resources/agent-quickstart`,
+    { redirect: "manual" },
+  );
+
+  assert.equal(slug.status, 308);
+  assert.equal(
+    slug.headers.get("location"),
+    `${docsBasePath}/docs/community/ai-resources`,
+  );
+
+  // A retired per-page Markdown URL must stay Markdown: it has to redirect to
+  // the new .md route, not fall through to the HTML page.
+  const markdown = await fetch(
+    `${docsSiteUrl}${docsBasePath}/docs/ai-resources/agent-quickstart.md`,
+    { redirect: "manual" },
+  );
+
+  assert.equal(markdown.status, 308);
+  assert.equal(
+    markdown.headers.get("location"),
+    `${docsBasePath}/docs/community/ai-resources.md`,
+  );
+
+  // Following that redirect end to end must land on Markdown, not HTML.
+  const followed = await fetch(
+    `${docsSiteUrl}${docsBasePath}/docs/ai-resources/agent-quickstart.md`,
+  );
+
+  assert.equal(followed.status, 200);
+  assert.match(followed.headers.get("content-type") ?? "", /text\/markdown/);
+});
+
 test("/ redirects into the /ktx docs site", async () => {
   const response = await fetch(`${docsSiteUrl}/`, {
     redirect: "manual",