Add comprehensive emergency runbook documentation

Created docs/EMERGENCY_RUNBOOK.md with detailed procedures for:

Critical Incidents:
- Circuit breaker triggered (exit code 100)
- State rollback detected on startup
- Network-wide rollback scenarios
- Deployment failures
- Monitoring alerts

For Each Incident:
- Clear symptoms and what they mean
- Immediate actions to take
- Diagnosis procedures
- Recovery options with commands
- Prevention strategies

Includes:
- Emergency contact information
- Escalation matrix (P0-P3 severity levels)
- Testing procedures (testnet only)
- Useful command reference
- Post-incident review template

Procedures cover:
- Log preservation
- State inspection
- Fast-sync recovery
- Checkpoint restoration
- Coordinated validator recovery
- Emergency backups

All procedures include actual bash commands that can be
copy-pasted in emergency situations.

This is critical operational documentation for mainnet safety.
Operators can follow step-by-step procedurOperators can follow step-by-step procedurOperators can folduring an emergency.

Part of Week 6: Integration Tests and Documentation

Author: UltraDAGcom