Internationalize validation error message

Replaced hardcoded "Validation failed" message with translated
version from language files:
- Updated userProfileActions.ts to use t("validation-failed")
- Added translations in English and Croatian
- Reordered general-error div in AccountForm for better layout

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

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

messages/hr.json

@@ -150,7 +150,8 @@
     "save-button": "Spremi",
     "cancel-button": "Odbaci",
     "validation": {
-      "iban-invalid": "Neispravan IBAN format. Molimo unesite ispravan IBAN."
+      "iban-invalid": "Neispravan IBAN format. Molimo unesite ispravan IBAN.",
+      "validation-failed": "Validacija nije uspjela. Molimo provjerite formu i pokušajte ponovno."
     }
   }
 }