migrate mui from v5 to v6

[Forfold]

MUI v5 → v6 Upgrade

Package changes

• @mui/material: 5.16.7 → 6.5.0
• @mui/icons-material: 5.16.7 → 6.5.0
• @mui/system: 5.16.7 → 6.5.0
• @mui/styles: 5.16.7 → 6.5.0
• @mui/lab: removed (only used for LoadingButton, now built into Button)
• Added react-is override for React 18 compatibility

Code changes

• AdminSWOStatusCard.tsx — LoadingButton from @mui/lab → Button from @mui/material (v6 has native loading/loadingPosition props)
• NavBarLink.tsx, CreateAlertServiceSelect.tsx, DetailsPage.tsx — <ListItem button> → <ListItemButton>
• PaginatedList.tsx, FlatListItem.tsx — migrated to ListItemButton for interactive items
• FlatList.tsx — FlatListItemOptions changed to standalone interface (was extending ListItemProps which lost selected/button in v6)
• AdminSection.tsx — replaced removed selected prop with sx={{ bgcolor: 'action.selected' }}

Intentionally deferred for v7/v9

• @mui/styles/makeStyles migration (~86 files) — still works with @mui/styles@6.5.0
• Deprecated API migrations (slots/slotProps, system props, etc.) — all optional warnings in v6