feat: create v2-prep branch with comprehensive planning

Restructured project for V2 refactor:

**Structure Changes:**
- Moved all V1 code to orig/ folder (preserved with git mv)
- Created docs/planning/ directory
- Added orig/README_V1.md explaining V1 preservation

**Planning Documents:**
- 00_V2_MASTER_PLAN.md: Complete architecture overview
  - Executive summary of critical V1 issues
  - High-level component architecture diagrams
  - 5-phase implementation roadmap
  - Success metrics and risk mitigation

- 07_TASK_BREAKDOWN.md: Atomic task breakdown
  - 99+ hours of detailed tasks
  - Every task < 2 hours (atomic)
  - Clear dependencies and success criteria
  - Organized by implementation phase

**V2 Key Improvements:**
- Per-exchange parsers (factory pattern)
- Multi-layer strict validation
- Multi-index pool cache
- Background validation pipeline
- Comprehensive observability

**Critical Issues Addressed:**
- Zero address tokens (strict validation + cache enrichment)
- Parsing accuracy (protocol-specific parsers)
- No audit trail (background validation channel)
- Inefficient lookups (multi-index cache)
- Stats disconnection (event-driven metrics)

Next Steps:
1. Review planning documents
2. Begin Phase 1: Foundation (P1-001 through P1-010)
3. Implement parsers in Phase 2
4. Build cache system in Phase 3
5. Add validation pipeline in Phase 4
6. Migrate and test in Phase 5

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

orig/pkg/arbitrum/circuit_breaker.go

@@ -0,0 +1,182 @@
+package arbitrum
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/fraktal/mev-beta/internal/logger"
+)
+
+// CircuitBreakerState represents the state of a circuit breaker
+type CircuitBreakerState int
+
+const (
+	// Closed state - requests are allowed
+	Closed CircuitBreakerState = iota
+	// Open state - requests are blocked
+	Open
+	// HalfOpen state - limited requests are allowed to test if service recovered
+	HalfOpen
+)
+
+// String returns a string representation of the circuit breaker state
+func (state CircuitBreakerState) String() string {
+	switch state {
+	case Closed:
+		return "Closed"
+	case Open:
+		return "Open"
+	case HalfOpen:
+		return "HalfOpen"
+	default:
+		return fmt.Sprintf("Unknown(%d)", int(state))
+	}
+}
+
+// CircuitBreakerConfig represents the configuration for a circuit breaker
+type CircuitBreakerConfig struct {
+	// FailureThreshold is the number of failures that will trip the circuit
+	FailureThreshold int
+	// Timeout is the time the circuit stays open before trying again
+	Timeout time.Duration
+	// SuccessThreshold is the number of consecutive successes needed to close the circuit
+	SuccessThreshold int
+}
+
+// CircuitBreaker implements the circuit breaker pattern for RPC connections
+type CircuitBreaker struct {
+	state                CircuitBreakerState
+	failureCount         int
+	consecutiveSuccesses int
+	lastFailure          time.Time
+	config               *CircuitBreakerConfig
+	logger               *logger.Logger
+	mu                   sync.RWMutex
+}
+
+// NewCircuitBreaker creates a new circuit breaker with the given configuration
+func NewCircuitBreaker(config *CircuitBreakerConfig) *CircuitBreaker {
+	if config == nil {
+		config = &CircuitBreakerConfig{
+			FailureThreshold: 5,
+			Timeout:          30 * time.Second,
+			SuccessThreshold: 3,
+		}
+	}
+
+	// Ensure sensible defaults
+	if config.FailureThreshold <= 0 {
+		config.FailureThreshold = 5
+	}
+	if config.Timeout <= 0 {
+		config.Timeout = 30 * time.Second
+	}
+	if config.SuccessThreshold <= 0 {
+		config.SuccessThreshold = 3
+	}
+
+	return &CircuitBreaker{
+		state:                Closed,
+		failureCount:         0,
+		consecutiveSuccesses: 0,
+		lastFailure:          time.Time{},
+		config:               config,
+		logger:               nil,
+		mu:                   sync.RWMutex{},
+	}
+}
+
+// Call executes a function through the circuit breaker
+func (cb *CircuitBreaker) Call(ctx context.Context, fn func() error) error {
+	cb.mu.Lock()
+	defer cb.mu.Unlock()
+
+	// Check if circuit should transition from Open to HalfOpen
+	if cb.state == Open && time.Since(cb.lastFailure) > cb.config.Timeout {
+		cb.state = HalfOpen
+		cb.consecutiveSuccesses = 0
+	}
+
+	// If circuit is open, reject the call
+	if cb.state == Open {
+		return fmt.Errorf("circuit breaker is open")
+	}
+
+	// Execute the function
+	err := fn()
+
+	// Update circuit state based on result
+	if err != nil {
+		cb.onFailure()
+		return err
+	}
+
+	cb.onSuccess()
+	return nil
+}
+
+// onFailure handles a failed call
+func (cb *CircuitBreaker) onFailure() {
+	cb.failureCount++
+	cb.lastFailure = time.Now()
+
+	// Trip the circuit if failure threshold is reached
+	if cb.state == HalfOpen || cb.failureCount >= cb.config.FailureThreshold {
+		cb.state = Open
+		if cb.logger != nil {
+			cb.logger.Warn(fmt.Sprintf("Circuit breaker OPENED after %d failures", cb.failureCount))
+		}
+	}
+}
+
+// onSuccess handles a successful call
+func (cb *CircuitBreaker) onSuccess() {
+	// Reset failure count when in Closed state
+	if cb.state == Closed {
+		cb.failureCount = 0
+		return
+	}
+
+	// In HalfOpen state, count consecutive successes
+	if cb.state == HalfOpen {
+		cb.consecutiveSuccesses++
+		// Close circuit if enough consecutive successes
+		if cb.consecutiveSuccesses >= cb.config.SuccessThreshold {
+			cb.state = Closed
+			cb.failureCount = 0
+			cb.consecutiveSuccesses = 0
+			if cb.logger != nil {
+				cb.logger.Info("Circuit breaker CLOSED after successful recovery")
+			}
+		}
+	}
+}
+
+// GetState returns the current state of the circuit breaker
+func (cb *CircuitBreaker) GetState() CircuitBreakerState {
+	cb.mu.RLock()
+	defer cb.mu.RUnlock()
+	return cb.state
+}
+
+// Reset resets the circuit breaker to closed state
+func (cb *CircuitBreaker) Reset() {
+	cb.mu.Lock()
+	defer cb.mu.Unlock()
+	cb.state = Closed
+	cb.failureCount = 0
+	cb.consecutiveSuccesses = 0
+	cb.lastFailure = time.Time{}
+	if cb.logger != nil {
+		cb.logger.Info("Circuit breaker reset to closed state")
+	}
+}
+
+// SetLogger sets the logger for the circuit breaker
+func (cb *CircuitBreaker) SetLogger(logger *logger.Logger) {
+	cb.mu.Lock()
+	defer cb.mu.Unlock()
+	cb.logger = logger
+}