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>
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