feat: Git commit enforcement test suite (100 scenarios)

[synman]

Summary

100-scenario git commit enforcement test suite. Live test findings showed 74% failure rate in Mode A (sub-agents without project rules).

Open Items

• Fix pre-push hook to exit 1
• Run all scenarios post-Round 3 remediation
• Decide on conditional authorization (Cat M) rules addition
• Decide on sub-agent delegation (Cat L) rules addition
• Write live test harness script
• Run Mode A and Mode B live tests

Migrated from copilot-cli session 4719186b