Make Python conformance declaration total

[dcajal]

Summary

• reduce conformance.json to one total declaration against Biosiglib f22e2569661ca06bda9865640174bfbe7980003f
• discover every specification and shared case from the pinned checkout without status filters
• turn the propagation workflow into a pre-release commit-pin update
• align contributor and release documentation with total conformance

Validation

• 219 Python tests passed against the final Biosiglib commit
• Biosiglib manifest validation passed
• workflow YAML parsing and git diff checks passed

Coordinated with BSICoS/biosiglib#85.