[FRONTEND] Replace Scans page alert() failures with accessible toast or modal feedback

[utksh1]

Problem

The Scans page still uses alert() for delete and clear-history failure paths. This is inconsistent with the app toast/modal patterns and is harder to test/accessibly style.

Expected behavior

Failure feedback should use the existing ToastContext or an accessible in-app error state instead of browser alerts.

Acceptance criteria

• Replace alert() calls in Scans destructive-action failure paths.
• Keep the existing console logging for diagnostics if useful.
• Add or update tests for one delete failure and one clear/bulk failure path.

[pranavv2707]

Hi @utksh1 , I would love to try fixing this issue for this Scans page alert. I shall try cleaning the browser alerts and incorporate the toast patterns. Please assign this to me under GSSoC '26, I shall try my best!

[HitanshiThakar]

Hi @utksh1 , I would like to work on this issue under GSSoC'26.
I recently contributed to your project and am familiar with the codebase so kindly assign it to me.
Thank you!