v1.0.21 - AHE preflight audit

v1.0.21 - AHE preflight audit

What's new

• Added an integrated AHE preflight audit step before /evolve evaluation.
• Added scripts/preflight-audit.mjs to generate preflight-audit.json per iteration.
• The preflight artifact includes:
  • contract coverage
  • runtime evidence coverage
  • doc/runtime alignment
  • drift severity
  • doc/runtime matrix
  • prioritized recommendations
  • confidence level
• Updated /evolve so preflight runs before session staging, evaluator, debugger, and evolver.
• Added audit-only as a lightweight branch for harness status/audit without invoking sidecars.
• Updated evaluator, debugger, and evolver contracts to consume preflight output as baseline evidence.
• Added checker enforcement and tests so the preflight contract cannot drift silently.