add items per wagon map to cargo types and sync bulk rate units

- Implemented  in the  to manage the physical item capacity for each wagon type.
- Added a new migration to create the  column in the  table.
- Introduced  method in  to update rate units when cargo type unit of measure changes.
- Updated booking calculations to consider items per wagon for break-bulk cargo.
- Refactored various components to utilize the new items fit logic and ensure consistent date formatting across the application.
- Added tests for the new display timezone functionality to ensure consistent date/time representation across different user settings.

apps/edr-freight-web/backoffice/src/main.tsx

@@ -1,3 +1,6 @@
+// Must stay the first import: pins all date/time display to EAT before any
+// module can create a formatter in the PC's local timezone.
+import "@edr/ui-common/display-timezone";
 import { StrictMode } from "react";
 import { createRoot } from "react-dom/client";
 import { BrowserRouter } from "react-router-dom";