feat: add validation for Revolut profile name format

- Add ownerRevolutProfileName field validation when enableRevolutPayment is true
- Validate profile name must start with '@' and contain only letters and numbers
- Add required field validation for Revolut profile name
- Add English and Croatian error messages for validation failures
- Update State type to include ownerRevolutProfileName errors

Validation regex: /^@[a-zA-Z0-9]+$/
Valid examples: @john123, @ivan, @user2024

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

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

messages/hr.json

@@ -236,6 +236,8 @@
       "owner-iban-required": "Ispravan IBAN je obavezan",
       "owner-iban-invalid": "Neispravan IBAN format. Molimo unesite ispravan IBAN.",
       "currency-required": "Valuta je obavezna",
+      "owner-revolut-profile-required": "Naziv Revolut profila je obavezan",
+      "owner-revolut-profile-invalid": "Neispravan format Revolut profila. Mora počinjati sa '@' i sadržavati samo slova i brojeve (npr. '@ivan123')",
       "validation-failed": "Validacija nije uspjela. Molimo provjerite formu i pokušajte ponovno."
     },
     "payment-additional-notes": "VAŽNO: da bi upute za uplatu bile prikazane podstanaru, morate tu ovu opciju uključiti i u postavkama pripadajuće nekretnine."