Add end field to task creation panel

[Hell1213]

Implemented end date picker in AddTaskDialog for setting task completion dates. Backend now handles end field with proper validation and storage. Updated all related types, handlers and tests to support task end date functionality.

Added end date field to the task creation panel. Users can now specify when they plan to complete a task using the date picker component. Backend processes the end field and passes it to Taskwarrior with proper formatting.

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

The end field appears between Start and Recur fields in the Add Task dialog, following the same implementation pattern as other date fields.

Demo Video :

Screencast.from.2025-12-23.03-19-33.mp4

[github-actions]

Thank you for opening this PR!

Before a maintainer takes a look, it would be really helpful if you could walk through your changes using GitHub's review tools.

Please take a moment to:

• Check the "Files changed" tab
• Leave comments on any lines for functions, comments, etc. that are important, non-obvious, or may need attention
• Clarify decisions you made or areas you might be unsure about and/or any future updates being considered.
• Finally, submit all the comments!

More information on how to conduct a self review:
https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/reviewing-proposed-changes-in-a-pull-request

This helps make the review process smoother and gives us a clearer understanding of your thought process.

Once you've added your self-review, we'll continue from our side. Thank you!

[Hell1213]

Completed self-review. End field implementation follows the same pattern as start field - clean, consistent, and fully tested. All backend/frontend integration working properly.

[Hell1213]

@its-me-abhishek
Pr is ready for review .

[Neeraj-gagat]

Hey, @Hell1213 I noticed this PR overlaps with mine #293
I opened mine a bit earlier and it addresses same end field Happy to coordinate or adjust if needed 🙂

[Hell1213]

Hey, @Hell1213 I noticed this PR overlaps with mine #293 I opened mine a bit earlier and it addresses same end field Happy to coordinate or adjust if needed 🙂

Thanks for pointing this out, Neeraj
I wasn’t aware of PR #293 when I started this.
Happy to coordinate or adjust based on @its-me-abhishek preference.

[its-me-abhishek]

Fixed by #293