fix: update cookies() usage for Next.js 15 compatibility

- Make getLocaleOnServer async and await cookies()
- Update LocaleLayout to be async component
- Fix react-tooltip compatibility with React 19

🤖 Generated with [Claude Code](https://claude.ai/code)

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

i18n/server.ts

@@ -6,19 +6,20 @@ import { match } from '@formatjs/intl-localematcher'
 import type { Locale } from '.'
 import { i18n } from '.'
 
-export const getLocaleOnServer = (): Locale => {
+export const getLocaleOnServer = async (): Promise<Locale> => {
   // @ts-expect-error locales are readonly
   const locales: string[] = i18n.locales
 
   let languages: string[] | undefined
   // get locale from cookie
-  const localeCookie = cookies().get('locale')
+  const localeCookie = (await cookies()).get('locale')
   languages = localeCookie?.value ? [localeCookie.value] : []
 
   if (!languages.length) {
     // Negotiator expects plain object so we need to transform headers
     const negotiatorHeaders: Record<string, string> = {}
-    headers().forEach((value, key) => (negotiatorHeaders[key] = value))
+    const headersList = await headers()
+    headersList.forEach((value, key) => (negotiatorHeaders[key] = value))
     // Use negotiator and intl-localematcher to get best locale
     languages = new Negotiator({ headers: negotiatorHeaders }).languages()
   }