Add info box to account form explaining barcode usage

Added informational alert at the top of the account form to explain
that profile data (name, address, IBAN) will be used to generate 2D
barcodes for tenant bill payments. The alert uses a horizontal layout
on all screen sizes for consistent UX.

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

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

messages/en.json

@@ -138,6 +138,7 @@
   },
   "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.",
     "first-name-label": "First Name",
     "first-name-placeholder": "Enter your first name",
     "last-name-label": "Last Name",