Rename 'iban' to 'ownerIBAN' in UserSettings

Changes:
- Updated UserSettings interface: iban -> ownerIBAN
- Updated userSettingsActions.ts:
  - Changed State type to use ownerIBAN
  - Updated FormSchema validation to reference ownerIBAN
  - Updated validation refinements to check ownerIBAN
  - Updated form data parsing to read ownerIBAN
  - Renamed normalizedIban to normalizedOwnerIBAN
  - Updated database write operations to use ownerIBAN
- Updated UserSettingsForm.tsx:
  - Changed state tracking to use ownerIBAN
  - Updated validation check to reference ownerIBAN (cleanedOwnerIBAN)
  - Updated input field: id, name, and event handlers
- Updated ViewLocationCard.tsx to use ownerIBAN instead of iban
- Updated English translations:
  - iban-label -> owner-iban-label
  - iban-placeholder -> owner-iban-placeholder
  - iban-required -> owner-iban-required
  - iban-invalid -> owner-iban-invalid
- Updated Croatian translations with corresponding ownerIBAN keys

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

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

app/lib/db-types.ts

@@ -24,8 +24,8 @@ export interface UserSettings {
     ownerStreet?: string | null;
     /** owner town */
     ownerTown?: string | null;
-    /** IBAN */
-    iban?: string | null;
+    /** owner IBAN */
+    ownerIBAN?: string | null;
     /** currency (ISO 4217) */
     currency?: string | null;
     /** whether to show 2D code in monthly statement */