Rename csv2vcd.c.org to csv2vcd.org.c

MO: added comments to test_csv2vcd.py

MO: make help added pytest, c source more comments, bigger buffer size.

Ignore Python caches and local venv

Improve pytest visibility and fixture reporting

Clarify code flow with comments across sources

Add headers and comments to helper scripts

Add PowerShell and pytest test harnesses

Add cross-platform build system and project infrastructure

Add original csv2vcd.c backup

Initial commit: csv2vcd converter with tests and examples