fix(compilation): resolve type system and interface errors

- Add GetPoolsByToken method to cache interface and implementation
- Fix interface pointer types (use interface not *interface)
- Fix SwapEvent.TokenIn/TokenOut usage to use GetInputToken/GetOutputToken methods
- Fix ethereum.CallMsg import and usage
- Fix parser factory and validator initialization in main.go
- Remove unused variables and imports

WIP: Still fixing main.go config struct field mismatches

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

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

pkg/arbitrage/path_finder.go

@@ -37,13 +37,13 @@ func DefaultPathFinderConfig() *PathFinderConfig {
 
 // PathFinder finds arbitrage paths between tokens
 type PathFinder struct {
-	cache  *cache.PoolCache
+	cache  cache.PoolCache
 	config *PathFinderConfig
 	logger *slog.Logger
 }
 
 // NewPathFinder creates a new path finder
-func NewPathFinder(cache *cache.PoolCache, config *PathFinderConfig, logger *slog.Logger) *PathFinder {
+func NewPathFinder(cache cache.PoolCache, config *PathFinderConfig, logger *slog.Logger) *PathFinder {
 	if config == nil {
 		config = DefaultPathFinderConfig()
 	}
@@ -427,11 +427,11 @@ func (pf *PathFinder) getCommonTokens(ctx context.Context, baseToken common.Addr
 	// ARB
 	arb := common.HexToAddress("0x912CE59144191C1204E64559FE8253a0e49E6548")
 
-	common := []common.Address{weth, usdc, usdt, dai, arb}
+	commonTokens := []common.Address{weth, usdc, usdt, dai, arb}
 
 	// Filter out the base token itself
 	filtered := make([]common.Address, 0)
-	for _, token := range common {
+	for _, token := range commonTokens {
 		if token != baseToken {
 			filtered = append(filtered, token)
 		}