fix(validation): expand validate_url edge case coverage

[HitanshiThakar]

Description

Added additional validate_url test coverage in testing/backend/unit/test_validation.py for edge cases including:

localhost URLs with paths and query parameters
IP addresses with ports
invalid schemes
missing hosts
malformed ports
URLs containing spaces

While adding the tests, I found that malformed/out-of-range ports were being accepted as valid URLs. Added a small validation fix to reject invalid port values.

Related Issues

Closes #80

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

python -m pytest testing/backend/unit/test_validation.py -v

Result:

6 tests passed

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]

CI currently shows backend-tests failing. Please rebase on latest main and re-run CI; if failures persist, fix them.

After checks are green, I can re-review the URL validation coverage changes.

[HitanshiThakar]

Done, All checks have passed.