refactor: update Dockerfile and authentication flow for improved user experience

- Updated Dockerfile to create a cache directory for Next.js runtime, ensuring proper permissions and ownership.
- Enhanced the authentication flow by updating the magic link expiration time from 5 to 15 minutes, improving user experience and reducing login issues.
- Added user-friendly error handling for invalid or expired magic links, providing clear feedback on the login page.
- Adjusted email templates to reflect the new 15-minute validity period for magic links.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/lib/rapor-maske.ts

@@ -48,5 +48,8 @@ export function raporMaskele(rapor: RaporSonuc): MaskeliRapor {
     kilitliUyariSayisi: Math.max(0, (rapor.uyarilar?.length ?? 0) - 1),
     // Program adı, üniversite ve 2021–2025 taban sıralamaları ham veridir.
     programlar: rapor.programlar,
+    // Kapsam (kaç program bulundu / dağılım uyarlandı mı) dürüstlük bilgisi:
+    // paketsiz kullanıcı da görür, maskelenmez.
+    kapsam: rapor.kapsam,
   };
 }