feat: implement US-1 - add print button to MonthCard with i18n support

- Add PrintButton component with card styling matching AddLocationButton
- Integrate print button next to "Add a new realestate" with centered layout
- Add English/Croatian translations for print tooltips and labels
- Implement click handler to open print preview in new tab
- Create Sprint Playbook for barcode print functionality

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

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

messages/en.json

@@ -58,7 +58,9 @@
       "link-copy-message": "Link copied to clipboard"
     },
     "month-card": {
-      "payed-total-label": "Total monthly expenditure:"
+      "payed-total-label": "Total monthly expenditure:",
+      "print-codes-tooltip": "Print 2D codes",
+      "print-codes-label": "Print codes"
     }
   },
   "bill-delete-form": {