feat(ai): localize AI features

keep-notes/app/api/ai/suggest-notebook/route.ts

@@ -10,7 +10,7 @@ export async function POST(req: NextRequest) {
     }
 
     const body = await req.json()
-    const { noteContent } = body
+    const { noteContent, language = 'en' } = body
 
     if (!noteContent || typeof noteContent !== 'string') {
       return NextResponse.json({ error: 'noteContent is required' }, { status: 400 })
@@ -29,7 +29,8 @@ export async function POST(req: NextRequest) {
     // Get suggestion from AI service
     const suggestedNotebook = await notebookSuggestionService.suggestNotebook(
       noteContent,
-      session.user.id
+      session.user.id,
+      language
     )
 
     return NextResponse.json({