Adds CloneDivergenceCheck that detects when git clones have drifted significantly behind origin/main: - >10 commits behind: WARNING - >50 commits behind: ERROR (EMERGENCY) Only checks clones on main branch, since off-main clones are already caught by BranchCheck. This distinguishes from beads-sync divergence which is expected behavior. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>