Closes#21608
The Tasks Calendar renders an empty grid because `GroupByTasks` fails
with `Field "deletedAt" is not supported in groupBy` while the header
count (`AggregateTasks`) still succeeds.
The calendar renders by grouping records on the selected date field.
Calendar-field eligibility only checked `isFieldMetadataDateKind`, so
`deletedAt` (a system DATE_TIME field) could be picked or auto-defaulted
as the calendar field — and the groupBy engine correctly rejects it
(only `createdAt`/`updatedAt` are groupable system date fields).
Fix: gate calendar-field eligibility on
`isFieldMetadataSupportedInGroupBy` (the same authority the backend
groupBy validator uses), so non-groupable date fields can no longer be
selected.
- `useGetAvailableFieldsForCalendar` — add the groupBy-support check
alongside the date-kind filter
- `ObjectOptionsDropdownCalendarFieldsContent` — reuse the hook's list
instead of re-filtering raw fields
nitin
9bc0db5666