Display Timefence version in audit/build report headers

[gauthierpiarrette]

For reproducibility, the terminal output and JSON manifests from build and audit should include the Timefence version used to generate them. This helps when debugging issues across environments.

Steps:

1. Import version from _version.py
2. Add to the Rich console header in audit/build output
3. Add to the JSON manifest
4. Add test