fix: getPrefs sonucunu plain object'e çevir (Server→Client prop hatası)

src/app/(dashboard)/layout.tsx

@@ -17,7 +17,10 @@ export default async function DashboardLayout({
   let themePrefs: ThemePrefs = {};
   try {
     const { account } = await createSessionClient();
-    themePrefs = await account.getPrefs<ThemePrefs>();
+    const raw = await account.getPrefs<ThemePrefs>();
+    // getPrefs returns an Appwrite prototype object — serialize to plain object
+    // so Next.js can pass it from Server → Client Component
+    themePrefs = JSON.parse(JSON.stringify(raw)) as ThemePrefs;
   } catch {
     // use defaults if prefs unavailable
   }