fix: prevent slider thumbs from being keyboard focusable when readonly or disabled

[vpai-2-eightfold]

SUMMARY:

Fixes accessibility issue where slider thumbs (<input type="range"> elements) remained keyboard focusable even when the slider was in readOnly or disabled state. This prevented users from skipping non-interactive sliders during keyboard navigation.

GITHUB ISSUE (Open Source Contributors)

N/A

JIRA TASK (Eightfold Employees Only):

https://eightfoldai.atlassian.net/browse/ENG-164476

CHANGE TYPE:

• Bugfix Pull Request
• Feature Pull Request

TEST COVERAGE:

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

TEST PLAN:

Automated Tests
✅ Added 2 new unit tests in Slider.test.tsx:

1. Test 1: Verifies tabIndex="-1" is set on thumb inputs when slider is readOnly or disabled
2. Test 2: Verifies tabIndex attribute is not present on thumb inputs when slider is interactive

✅ All existing tests pass

Manual Testing

1. Test readonly slider:

   • Create a slider with readOnly={true}
   • Press Tab key to navigate through the page
   • Expected: Slider thumbs are skipped in tab order

2. Test disabled slider:

   • Create a slider with disabled={true}
   • Press Tab key to navigate through the page
   • Expected: Slider thumbs are skipped in tab order

3. Test interactive slider:

   • Create a normal slider (no readonly/disabled props)
   • Press Tab key to navigate through the page
   • Expected: Slider thumbs receive focus and can be controlled with arrow keys

4. Test range slider:

   • Create a range slider with readOnly={true}
   • Press Tab key to navigate
   • Expected: Both thumbs are skipped in tab order

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.21%. Comparing base (1dc8501) to head (811ba3e).
⚠️ Report is 19 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1082      +/-   ##
==========================================
+ Coverage   84.09%   84.21%   +0.11%     
==========================================
  Files        1162     1146      -16     
  Lines       20976    21045      +69     
  Branches     7932     8000      +68     
==========================================
+ Hits        17639    17722      +83     
+ Misses       3249     3235      -14     
  Partials       88       88              

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