Vue client: add shared area assignment to scripts and devices ...

- Add useAreaAssign composable for reusable area assignment logic
- Add AreaBadgeLink and AreaAssignSection shared components
- Integrate area assignment into ScriptDetailPage (actions/regular)
- Integrate area assignment into DeviceDetailPage
- Update scriptsStore with assignToArea / unassignFromArea + reactivity fixes
- Update API modules: scripts.placeInArea, devices.assignToArea
- Update list views: show area badges in actions/regular cards and tables
- Add tests and mock handlers for script area operations
- Update AppShell nav and routes for detail pages
- Add prism-theme.css for code highlighting
- 125 tests passing, build green