VSN-2590 — Migrate staff email history page to shadcn with unified table design

Summary

Email History (/dashboard/staff/email) — 6 files

• List view (email-list-view.tsx): Replaced MUI Box/Stack/Menu/TableManager with CSS grid table using TableHeadCustom with #DBD7F9 purple header, shadcn TableControlBar/TabsCustom/TablePagination, skeleton loading states, proper z-index layering for controls
• Table row (email-table-row.tsx): Replaced MUI TableCell/Checkbox/Chip/ContratStyledRow/SvgColor with CSS grid row — colored left border per status (green=sent, yellow=pending, red=failed), shadcn Checkbox, Tailwind status badges, Lucide Eye (view) and RefreshCw (resend) action icons with colored hover states
• Detail modal (email-detail-modal.tsx): Replaced MUI Dialog/Paper/Collapse/Chip with shadcn Dialog — dark purple gradient header with email-client layout (De/À/Date with UserCircle/AtSign/CalendarDays icons), status pill with contextual icon (Send/Clock/XCircle), clean email body area, attachment strip with download hover effect, collapsible error logs with AlertTriangle
• Filters (email-filters.tsx): Replaced MUI Accordion/TextField/Checkbox/DatePicker with shadcn Checkbox/Input/Button, native date inputs, Lucide icons (Filter/Calendar/Search)
• Export (email-export.tsx): Replaced MUI Menu/MenuItem with shadcn DropdownMenu — colored Lucide icons (PDF FileText red, CSV Table2 green, Print Printer blue), simplified API (no anchor element needed)
• Page route (page.tsx): Removed MUI Box import

Files modified (6)

• src/app/dashboard/staff/email/page.tsx
• src/shared/sections/staff/historiqueEmail/view/email-list-view.tsx
• src/shared/sections/staff/historiqueEmail/view/email-table-row.tsx
• src/shared/sections/staff/historiqueEmail/components/email-detail-modal.tsx
• src/shared/sections/staff/historiqueEmail/components/email-filters.tsx
• src/shared/sections/staff/historiqueEmail/components/email-export.tsx Closes VSN-2590