Docs: refresh UI Guide screenshots for Airflow 3.1.x (dark/light)

[KatalKavya96]

---

Description

This PR updates the UI Guide documentation to reflect the refreshed Airflow 3.1.x UI.

• Re-captured all screenshots in both dark and light themes (1080p+, consistent zoom level).
• Updated :alt: text for accessibility and clarity.
• Verified that all image paths resolve correctly in docs/ui.rst.

These changes ensure that the UI Guide remains accurate and visually consistent for Airflow 3.1.x.

Related Issues

closes: #55521

Notes

• This PR covers UI Guide updates.
• A follow-up PR will handle DAG Runs screenshots (also part of Update Screenshots for Airflow 3.1.0 Release #55521).
• No code or provider changes are introduced in this PR.
• Newsfragment not required, as this is a documentation-only update.

[cmarteepants]

Great job! There's just one screenshot that should be updated (however is easiest).

[KatalKavya96]

@cmarteepants Fixed that last dag_list screenshot. I think its read to go now

[kaxil]

These blank lines are needed. Without it, the docs build fail:

https://github.com/apache/airflow/actions/runs/17862695877/job/50797945885?pr=55876

[KatalKavya96]

@kaxil I will handle all the above listed suggestions and recommit.

[KatalKavya96]

@kaxil @cmarteepants I have made the suggested changes.Kindly look into them

[KatalKavya96]

@kaxil I have replaced above listed 4 images (both light and dark). Please review it further

[KatalKavya96]

@kaxil I replaced dag_run_graph and dag_overview_grid with better screenshots.Please review once again.Thanks!

[KatalKavya96]

@ashb Ok , I will make the required changes and recommit

[ashb]

@KatalKavya96 No, I'm afraid not. There are still unresolved comments (even before I just reviewed it and added some more)

[ashb]

@KatalKavya96 Please can you go and review the side-by-side diff and see that they roughly match the old content before asking a review again. Thanks

[KatalKavya96]

@ashb Ok , I will once go for a side by side comparison for all changed images and make sure that they are the nearest to the original image, Thanks for the Review

[KatalKavya96]

@kaxil Thanks for the merge but all the files in ui.rst were not updated rightly in the docs after i tried to rebase. I was trying to fix this issue by adding all other left images, Since this PR has been merged let me raise another PR for the files which still remains not updated, Is it fine with you?

[kaxil]

Yes, please do it

[KatalKavya96]

@kaxil Please check the follow up PR #56000