feat(frontend): Preserve selected Scans filter in URL query params

[NiravaM]

Description

The Scans page status filter resets on refresh. Persist the selected filter in the URL query string so links can be shared and refreshes keep context.

Related Issues

closes #88

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

1. Manual Verification: Navigated to /scans, changed filter to "Completed". Verified URL updated to /scans?status=completed. Hit refresh, verified filter stayed on "Completed".
2. Fallback Verification: Manually typed /scans?status=invalid_status into the browser bar. Verified page loaded safely with the "All" filter active.
3. Automated Verification: Added/ran unit tests utilizing MemoryRouter to validate initial search parameter parsing.

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.