fix(docs): restore theme switch without runtime warnings

Move html/body shell and global css to root app layout to avoid hydration/script warnings from nested document nodes. Disable provider theme injection and add a custom script-free theme switch in shared layout slots.

Also migrate docs search static client initializer to ZBSearch (initDB), add zbsearch dependency, and align docs lint tooling with ESLint 9 compatibility so npm run lint passes.

docs/components/search-dialog.tsx

@@ -1,6 +1,6 @@
 'use client';
 
-import { create } from '@orama/orama';
+import { create } from 'zbsearch';
 import { useDocsSearch } from 'fumadocs-core/search/client';
 import { oramaStaticClient } from 'fumadocs-core/search/client/orama-static';
 import {
@@ -25,8 +25,8 @@ interface SharedProps {
 // default static dialog feeds those codes to Orama as a tokenizer language, but
 // Orama only accepts full names ("english") and throws on "en" — which silently
 // breaks search entirely. All docs content is English (other locales fall back
-// to it), so re-create the dialog — the documented escape hatch for custom Orama
-// setups — with an initOrama that always builds an English index.
+// to it), so re-create the dialog — the documented escape hatch for custom search
+// setups — with an initDB that always builds an English index.
 export default function SearchDialogClient(props: SharedProps) {
   const { locale } = useI18n();
   const client = useMemo(
@@ -34,7 +34,7 @@ export default function SearchDialogClient(props: SharedProps) {
       oramaStaticClient({
         from: '/api/search',
         locale,
-        initOrama: () => create({ schema: { _: 'string' }, language: 'english' }),
+        initDB: () => create({ schema: { _: 'string' }, language: 'english' }),
       }),
     [locale],
   );