feat: implement circuit breaker and emergency pause for all betting

[YahKazo]

• Add admin-only pause/unpause commands with configurable scope (BettingOnly/Full)
• Implement PauseScope enum for flexible pause control
• BettingOnly scope blocks betting (place_bet, place_bets) while allowing other operations
• Full scope blocks all betting, event creation, and operations
• Add configurable withdrawal permissions (allow_withdrawals flag) during pause
• Guards on place_bet, place_bets, create_event, and withdraw operations
• Return Error::CBOpen when operations blocked by circuit breaker state
• Comprehensive error handling with CB* error codes (500-503)
• Event emission for pause/unpause actions with admin, reason, scope tracking
• Add integration test test_pause_blocks_betting_and_unpause_restores()
• Security: Admin-only access enforced via AdminAccessControl with 'emergency_actions' permission
• Persist pause state in CircuitBreakerState with pause_scope and allow_withdrawals fields
• Complete documentation in CIRCUIT_BREAKER_IMPLEMENTATION.md

This implementation provides production-ready emergency pause functionality allowing admins to quickly pause betting or all operations during security incidents or emergencies, with granular control over which operations are blocked and whether withdrawals are permitted during pause.

Pull Request Description

📋 Basic Information closes #301

Type of Change

Please select the type of change this PR introduces:

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🧪 Test addition/update
• 🔧 Refactoring (no functional changes)
• ⚡ Performance improvement
• 🔒 Security fix
• 🎨 UI/UX improvement
• 🚀 Deployment/Infrastructure change

Related Issues

Closes #(issue number)
Fixes #(issue number)
Related to #(issue number)

Priority Level

• 🔴 Critical (blocking other development)
• 🟡 High (significant impact)
• 🟢 Medium (moderate impact)
• 🔵 Low (minor improvement)

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📝 Detailed Description

What does this PR do?

Why is this change needed?

How was this tested?

Alternative Solutions Considered

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🏗️ Smart Contract Specific

Contract Changes

Please check all that apply:

• Core contract logic modified
• Oracle integration changes (Pyth/Reflector)
• New functions added
• Existing functions modified
• Storage structure changes
• Events added/modified
• Error handling improved
• Gas optimization
• Access control changes
• Admin functions modified
• Fee structure changes

Oracle Integration

• Pyth oracle integration affected
• Reflector oracle integration affected
• Oracle configuration changes
• Price feed handling modified
• Oracle fallback mechanisms
• Price validation logic

Market Resolution Logic

• Hybrid resolution algorithm changed
• Dispute mechanism modified
• Fee structure updated
• Voting mechanism changes
• Community weight calculation
• Oracle weight calculation

Security Considerations

• Access control reviewed
• Reentrancy protection
• Input validation
• Overflow/underflow protection
• Oracle manipulation protection

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🧪 Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• All tests passing locally
• Manual testing completed
• Oracle integration tested
• Edge cases covered
• Error conditions tested
• Gas usage optimized
• Cross-contract interactions tested

Test Results

# Paste test output here
cargo test
# Expected output: X tests passed, Y tests failed

Manual Testing Steps

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📚 Documentation

Documentation Updates

• README updated
• Code comments added/updated
• API documentation updated
• Examples updated
• Deployment instructions updated
• Contributing guidelines updated
• Architecture documentation updated

Breaking Changes

Breaking Changes:

Migration Guide:

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🔍 Code Quality

Code Review Checklist

• Code follows Rust/Soroban best practices
• Self-review completed
• No unnecessary code duplication
• Error handling is appropriate
• Logging/monitoring added where needed
• Security considerations addressed
• Performance implications considered
• Code is readable and well-commented
• Variable names are descriptive
• Functions are focused and small

Performance Impact

• Gas Usage:
• Storage Impact:
• Computational Complexity:

Security Review

• No obvious security vulnerabilities
• Access controls properly implemented
• Input validation in place
• Oracle data properly validated
• No sensitive data exposed

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🚀 Deployment & Integration

Deployment Notes

• Network: Testnet/Mainnet
• Contract Address:
• Migration Required: Yes/No
• Special Instructions:

Integration Points

• Frontend integration considered
• API changes documented
• Backward compatibility maintained
• Third-party integrations updated

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📊 Impact Assessment

User Impact

• End Users:
• Developers:
• Admins:

Business Impact

• Revenue:
• User Experience:
• Technical Debt:

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✅ Final Checklist

Pre-Submission

• Code follows Rust/Soroban best practices
• All CI checks passing
• No breaking changes (or breaking changes are documented)
• Ready for review
• PR description is complete and accurate
• All required sections filled out
• Test results included
• Documentation updated

Review Readiness

• Self-review completed
• Code is clean and well-formatted
• Commit messages are clear and descriptive
• Branch is up to date with main
• No merge conflicts

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📸 Screenshots (if applicable)

🔗 Additional Resources

• Design Document:
• Technical Spec:
• Related Discussion:
• External Documentation:

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💬 Notes for Reviewers

Please pay special attention to:

Questions for reviewers:

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Thank you for your contribution to Predictify! 🚀