docs: migrate to native Fumadocs search & UI fixes (#12732)

Changes:

- **Search**: Replaced Inkeep with Fumadocs' native built-in search
(createFromSource). Removed @inkeep/cxkit-react and custom search
dialogs.

- **Hydration Fix**: Removed markdown links from ### headings in
egress.mdx (across all versions) to fix the <a inside a> DOM mismatch
error.

- **Console Fix**: Added the missing key prop to <VersionSelector/> in
the layout to resolve the React list warning.

---------

Co-authored-by: Florian Forster <[email protected]>
Co-authored-by: Claude Fable 5.1 <[email protected]>

apps/docs/app/api/search/route.ts

@@ -1,7 +1,32 @@
-import { source } from '@/lib/source';
-import { createFromSource } from 'fumadocs-core/search/server';
+import { getBreadcrumbItems } from 'fumadocs-core/breadcrumb';
+import { createSearchAPI } from 'fumadocs-core/search/server';
+import { source, versionSource } from '@/lib/source';
+import { getVersionFromUrl, LATEST_VERSION } from '@/lib/versions';
 
-export const { GET } = createFromSource(source, {
+// Both loaders share one index. Every entry is tagged with its docs version so the
+// client can scope results to the version being viewed (see app/providers.tsx).
+function indexPages(loader: typeof source | typeof versionSource, getTag: (url: string) => string) {
+  const tree = loader.getPageTree();
+
+  return loader.getPages().map((page) => ({
+    id: page.url,
+    url: page.url,
+    title: page.data.title,
+    description: page.data.description,
+    structuredData: page.data.structuredData,
+    // Sidebar path (e.g. "Deploy & Operate › Self-Hosted"), shown with each result.
+    breadcrumbs: getBreadcrumbItems(page.url, tree)
+      .map((item) => item.name)
+      .filter((name): name is string => typeof name === 'string'),
+    tag: getTag(page.url),
+  }));
+}
+
+export const { GET } = createSearchAPI('advanced', {
   // https://docs.orama.com/docs/orama-js/supported-languages
   language: 'english',
+  indexes: [
+    ...indexPages(source, () => LATEST_VERSION),
+    ...indexPages(versionSource, getVersionFromUrl),
+  ],
 });