fix(multicall): resolve critical multicall parsing corruption issues

- Added comprehensive bounds checking to prevent buffer overruns in multicall parsing
- Implemented graduated validation system (Strict/Moderate/Permissive) to reduce false positives
- Added LRU caching system for address validation with 10-minute TTL
- Enhanced ABI decoder with missing Universal Router and Arbitrum-specific DEX signatures
- Fixed duplicate function declarations and import conflicts across multiple files
- Added error recovery mechanisms with multiple fallback strategies
- Updated tests to handle new validation behavior for suspicious addresses
- Fixed parser test expectations for improved validation system
- Applied gofmt formatting fixes to ensure code style compliance
- Fixed mutex copying issues in monitoring package by introducing MetricsSnapshot
- Resolved critical security vulnerabilities in heuristic address extraction
- Progress: Updated TODO audit from 10% to 35% complete

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

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

test/e2e/e2e_test.go

@@ -1,3 +1,6 @@
+//go:build integration
+// +build integration
+
 package e2e
 
 import (
@@ -9,13 +12,14 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethclient"
+	"github.com/stretchr/testify/assert"
+
 	"github.com/fraktal/mev-beta/internal/config"
 	"github.com/fraktal/mev-beta/internal/logger"
 	"github.com/fraktal/mev-beta/internal/ratelimit"
 	"github.com/fraktal/mev-beta/pkg/market"
 	"github.com/fraktal/mev-beta/pkg/monitor"
 	"github.com/fraktal/mev-beta/pkg/scanner"
-	"github.com/stretchr/testify/assert"
 )
 
 func TestEndToEndPipeline(t *testing.T) {