refactor(labels): rename Vessel→Cost Centre and Account/Cost Centre→Account
All user-facing strings updated across 22 files. Backend field names
(vesselId, vessel relation, Vessel model) unchanged.
Vessel → Cost Centre
- Page titles: Vessel Management, Vessel Detail
- Sidebar nav item
- Form labels in New PO, Edit PO, Import PO, Manager Edit, Approvals Search
- Table column headers in Approvals, Dashboard, History, My Orders
- Filter dropdowns ("All vessels" → "All cost centres")
- vessel-form dialogs: Add/Edit/Create
- sites/[id] stat card label
- sites/page column header
- XLSX export row 7 label; PDF HTML label; CSV header
- "Vessel/Office Requisition Number" → "Cost Centre/Office Requisition Number"
- Breadcrumb in vessel detail; "Home port" → "Home site"
- spend-charts heading
- Validation error message
Account / Cost Centre → Account
- po-detail "Account / Budget Head"
- manager-edit-po-form "Account / Cost Centre"
- import-form "Account / Cost Centre"
- accounts/page heading "Account / Cost Centre Management"
- XLSX export "Budget head"; PDF HTML "Budget head"
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>