feat(DatePicker): add accessibility announcement for arrow key navigation

[ychhabra-eightfold]

SUMMARY:

This PR implements two key accessibility improvements for the DateTimePicker Range Picker component:

1. Focus Trap Support

• Added trapFocus prop support to OcRangePicker (defaults to false to prevent regressions)
• Implemented FocusTrap component wrapper when enabled
• Added proper keyboard handling (Escape key) and mouse event prevention
• Updated range picker generator to pass through trapFocus prop

2. Fixed Arrow Key Focus Behavior

• Root Issue: Range picker focus remained stuck on header elements when navigating with arrow keys, preventing proper date announcements for screen readers
• Root Cause: useCellProps hook returned undefined for range pickers, disabling focus management on date cells
• Solution: Modified useCellProps to always return cell props, enabling proper focus shifts to date cells
• Added missing partialRef to range picker's PartialContext for complete focus management

3. Announcement Support

• Added announceArrowKeyNavigation prop support for range picker when dropdown opens
• Screen reader now properly announces date changes during arrow key navigation

Result: Range picker now has the same accessibility experience as single picker - arrow key navigation properly shifts focus to date cells and announces changes.

GITHUB ISSUE (Open Source Contributors)

N/A - Internal accessibility improvement

JIRA TASK (Eightfold Employees Only):

[Please fill in JIRA task number]

CHANGE TYPE:

• Feature Pull Request
• Bugfix Pull Request

TEST COVERAGE:

• Tests for this change already exist
• I have added unittests for this change

TEST PLAN:

Manual Testing

1. Focus Trap (when enabled):

   • Open range picker with trapFocus={true}
   • Press Tab - focus should be trapped within the picker
   • Press Escape - picker should close and trap should disable

2. Arrow Key Focus Behavior:

   • Open range picker
   • Press Tab to focus header elements
   • Press arrow keys - focus should shift to date cells (previously stayed on header)
   • Screen reader should announce date changes during navigation

3. Announcement Support:

   • Enable screen reader
   • Open range picker with announceArrowKeyNavigation={true}
   • Should hear announcement about arrow key navigation availability

Automated Testing

• All existing tests pass
• No regressions introduced
• Focus behavior properly maintained
• Default trapFocus={false} prevents any breaking changes

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[tejaswini-s-c-eightfold]

I have verified the announcement with NVDA and without NVDA

1. With NVDA Screen reader the arrow navigation is not working
2. Without NVDA Screen reader it is working as I am able to navigate using the arrow keys

@ychhabra-eightfold @pmahajan-eightfold

Arrow.Navigation.for.Date.picker.mp4

[mfazil-eightfold]

lgtm

[codecov]

Codecov Report

❌ Patch coverage is 59.25926% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.45%. Comparing base (cc4688f) to head (15d096b).

Files with missing lines	Patch %	Lines
...mponents/DateTimePicker/Internal/OcRangePicker.tsx	47.61%	11 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1033      +/-   ##
==========================================
- Coverage   84.48%   84.45%   -0.04%     
==========================================
  Files        1104     1104              
  Lines       20801    20824      +23     
  Branches     7877     7893      +16     
==========================================
+ Hits        17573    17586      +13     
- Misses       3140     3150      +10     
  Partials       88       88              

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