feat: redesign /logs page with table UI and date range filter

- Replace timeline view with table layout (Time, Operator, Type, Message)
- Add date range filter using @mantine/dates DatePickerInput
- Add SegmentedControl for log type filter
- Disable App Logs and Settings menu on /dev
- Remove Activity Logs menu from /dev (moved to /logs)
- Add dateFrom/dateTo query params to /api/logs backend
- Import @mantine/dates/styles.css to fix datepicker styling

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/frontend/App.tsx

@@ -1,5 +1,6 @@
 import { ColorSchemeScript, MantineProvider, createTheme } from '@mantine/core'
 import '@mantine/core/styles.css'
+import '@mantine/dates/styles.css'
 import '@mantine/notifications/styles.css'
 import { ModalsProvider } from '@mantine/modals'
 import { Notifications } from '@mantine/notifications'