fix: delay object URL cleanup after downloads

[HitanshiThakar]

Description

Delays object URL cleanup in downloadFile to avoid revoking the URL before downloads begin in Safari.

Changes include:

• Delay URL.revokeObjectURL(url) by 1000ms after a.click().
• Preserve the existing download flow, including blob creation, filename handling, anchor setup, and click behavior.
• Add a focused regression test to verify that object URL cleanup occurs after the delay.

Related Issues

Closes #1848

Type of Change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Ran:
npm test -- exportUtils.test.ts

Checklist

• My code follows the code style of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.

[utksh1]

Focused Safari download fix with a deterministic timer regression test. The failed run contains the pre-existing saved-views baseline failure; main now passes. Approved once the branch is refreshed against current main so required checks rerun.