covguard-reporting

Report assembly and output metadata construction for covguard.

This crate owns responsibilities that sit above renderer output and below orchestration:

• Convert evaluation output into domain (covguard.report.v1) and cockpit (sensor.report.v1) reports.
• Build skip/error report pairs.
• Derive report reasons and debug metadata.
• Provide the diff-format heuristic used by orchestration validation.