feat: add rent-due share page for rent payment information

Created a new /share/rent-due/ page to display rent payment information
separately from utility bills.

Changes:
- Created /share/rent-due/[id]/ page structure with RentViewPage component
- Created ViewRentCard component to display rent amount and payment info
- Added uploadRentProofOfPayment action for tenant proof upload
- Added translation keys for rent-specific labels (en/hr)
- Updated rent email templates to link to /share/rent-due/ instead of /share/bills-due/
- Updated documentation to reflect new URL structure

The rent page displays:
- Rent amount
- IBAN or Revolut payment information with QR/barcode
- Rent proof of payment upload (when enabled)

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

web-app/messages/hr.json

@@ -79,7 +79,10 @@
       "payment-description-label": "Opis plaćanja:",
       "upload-proof-of-payment-legend": "Potvrda o uplati",
       "upload-proof-of-payment-label": "Ovdje možete priložiti potvrdu o uplati:",
-      "revolut-link-text": "Plati pomoću Revoluta"
+      "revolut-link-text": "Plati pomoću Revoluta",
+      "rent-amount-label": "Iznos najamnine:",
+      "upload-rent-proof-of-payment-legend": "Potvrda o uplati najamnine",
+      "upload-rent-proof-of-payment-label": "Ovdje možete priložiti potvrdu o uplati najamnine:"
     },
     "month-card": {
       "total-due-label": "Ukupno neplaćeno u mjesecu:",