test(AddTaskDialog): Add test suite for AddTaskDialog component

[ShivaGupta-14]

Description

Improved test coverage for the AddTaskDialog component. Previously, the component lacked proper test for newer fields like annotations, recurrence, and date pickers.

Changes:

• Reorganize tests into logical describe blocks for better readability
• Use test.each for Date Fields to eliminate repetitive test code
• Add comprehensive tests for Annotations
• Add tests for Recur field dropdown selection
• Add tests for Project field create new / select existing flow
• Cover edge cases: empty inputs, whitespace-only, duplicate prevention

Updates: #300

Checklist

• Ran npx prettier --write . (for formatting)
• Ran gofmt -w . (for Go backend)
• Ran npm test (for JS/TS testing)
• Added unit tests, if applicable
• Verified all tests pass
• Updated documentation, if needed

Additional Notes

Screenshots

• Before:
  
• After:
  

[github-actions]

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[its-me-abhishek]

Line # 194 is untested as per the console, please fix/provide some context for future

[ShivaGupta-14]

<SelectContent
  onWheel={(e) => e.stopPropagation()}  // Line 225
  className="max-h-60 overflow-y-auto"
>

As line 225 is a UX scroll prevention handler and as per guidelines mentioned in issue: 'focus should be on meaningful tests rather than coverage-only tests', I left this untested as it doesn't affect component behavior or state.

Also, Line 51 is a defensive check in getFilteredTasks(), but it's currently unreachable. Since the dropdown only appears when the search text is non-empty, this function never gets called with an empty search, so that condition is never hit.

Let me know what you prefer!