[MAINTENANCE] Create simple VISSIM testing case

[yunlishao]

Task Summary
Develop a minimal test scenario for validating VISSIM integration.

Why is this needed?
Currently lacking simple testing cases makes it difficult to validate VISSIM functionality and conduct quick integration tests.

Scope of Work

• Create a minimal VISSIM test scenario with simple network geometry
• Add to tests directory following existing test structure (similar to tests/CoordMerge)
• Include config.yaml, batch file for execution, and VISSIM network file
• Document test execution and expected behavior

Environment (if version-specific)

• VISSIM version: 2022

Risks or Dependencies
None

Additional Context (optional)

• VISSIM-specific documentation: doc/VISSIMdoc.md
• Reference existing tests in tests directory for structure