Refactor AccountForm with 2D code toggle and conditional validation

- Refactor AccountForm to use toggle for showing/hiding profile fields
- Add show2dCodeInMonthlyStatement field to UserProfile database schema
- Implement conditional validation: all fields mandatory when 2D code is enabled
- Update FormSchema with .refine() methods for firstName, lastName, address, and IBAN
- IBAN validation includes both presence check and format validation when required
- Add validation error messages to English and Croatian localization files
- Initialize toggle state from persisted database value
- Form fields conditionally displayed based on toggle state

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

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

messages/en.json

@@ -166,8 +166,9 @@
   },
   "account-form": {
     "title": "Profile Information",
-    "info-box-message": "This information will be used to generate a 2D barcode displayed in the bill view, allowing tenants to scan it and refund the money you have spent on paying utility bills in their name.",
-    "warning-missing-data": "Warning: Some profile fields are missing. The 2D barcode will not be displayed to tenants on the shared bill view until all fields are filled in.",
+    "info-box-message": "By activating this option, a 2D barcode will be included in the monthly statement sent to the tenant, allowing them to make a direct payment to your bank account.",
+    "tenant-2d-code-legend": "TENANT 2D CODE",
+    "tenant-2d-code-toggle-label": "include 2D code in monthly statements",
     "first-name-label": "First Name",
     "first-name-placeholder": "Enter your first name",
     "last-name-label": "Last Name",
@@ -179,6 +180,10 @@
     "save-button": "Save",
     "cancel-button": "Cancel",
     "validation": {
+      "first-name-required": "First name is mandatory",
+      "last-name-required": "Last name is mandatory",
+      "address-required": "Address is mandatory",
+      "iban-required": "Valid IBAN is mandatory",
       "iban-invalid": "Invalid IBAN format. Please enter a valid IBAN",
       "validation-failed": "Validation failed. Please check the form and try again."
     }