Replace billedToTenant boolean with billedTo enum

Migrated from boolean checkbox to enum-based radio buttons for better
flexibility and clarity in tracking bill payment responsibility.

Changes:
- Added BilledTo enum with values 'tenant' and 'landlord'
- Replaced Bill.billedToTenant (boolean) with Bill.billedTo (enum)
- Updated BillEditForm to use radio buttons instead of checkbox
- Updated billActions to handle billedTo enum values
- Updated all display filtering to use enum comparison
- Updated printActions barcode filtering
- Updated translations for radio button labels (en/hr)

The billedTo property is optional for backward compatibility -
undefined values default to BilledTo.Tenant, maintaining current
behavior where only tenant bills are displayed and calculated.

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

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

app/lib/actions/printActions.ts

@@ -1,7 +1,7 @@
 'use server';
 
 import { getDbClient } from '../dbClient';
-import { BillingLocation, Bill } from '../db-types';
+import { BilledTo, BillingLocation, Bill } from '../db-types';
 import { AuthenticatedUser } from '../types/next-auth';
 import { withUser } from '../auth';
 import { unstable_noStore as noStore } from 'next/cache';
@@ -42,7 +42,7 @@ export const fetchBarcodeDataForPrint = withUser(async (user: AuthenticatedUser,
     for (const location of locations) {
         for (const bill of location.bills) {
             // Only include bills that are billed to tenant and have barcode images
-            if (bill.barcodeImage && bill.barcodeImage.trim() !== "" && (bill.billedToTenant ?? true)) {
+            if (bill.barcodeImage && bill.barcodeImage.trim() !== "" && (bill.billedTo ?? BilledTo.Tenant) === BilledTo.Tenant) {
                 printData.push({
                     locationName: location.name,
                     billName: bill.name,