[TEST] Add Background component rendering contract tests

[utksh1]

Summary

Background is a shared visual component but no dedicated unit test surfaced in the scan.

Files found during scan

• frontend/src/components/Background.tsx

Acceptance criteria

• Render the component without crashing.
• Assert decorative layers are aria-hidden or non-interactive as appropriate.
• Keep the test independent of animation timing.

[Rakshak05]

Hii @utksh1, I would like to work on this. Can you please assign it to me under GSSoC'26 contributor!?

[karrisanthoshigayatri]

Hi @utksh1, I'd like to work on this issue under GSSoC'26.

Approach:

• Add dedicated unit tests for the Background component.
• Verify the component renders without crashing.
• Assert decorative layers are aria-hidden or non-interactive where appropriate.
• Keep the tests independent of animation timing and focused on rendering behavior.

Thank you!

[Rakshak05]

Hi @utksh1, I forgot to include Closes #1414 in my PR description, so the issue wasn't closed automatically after the PR was merged. Could you please close it manually? Thanks!