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/calculator.go

@@ -271,19 +271,13 @@ func (c *Calculator) calculateSwapOutputCurve(pool *types.PoolInfo, tokenIn, tok
 		return nil, 0, fmt.Errorf("pool has nil reserves")
 	}
 
-	// Determine direction
-	var reserveIn, reserveOut *big.Int
-	if tokenIn == pool.Token0 {
-		reserveIn = pool.Reserve0
-		reserveOut = pool.Reserve1
-	} else if tokenIn == pool.Token1 {
-		reserveIn = pool.Reserve1
-		reserveOut = pool.Reserve0
-	} else {
+	// Determine direction (validate token is in pool)
+	if tokenIn != pool.Token0 && tokenIn != pool.Token1 {
 		return nil, 0, fmt.Errorf("token not in pool")
 	}
 
 	// Simplified: assume 1:1 swap with low slippage for stablecoins
+	// TODO: Implement proper Curve StableSwap math using reserves and amp coefficient
 	// This is a rough approximation - actual Curve math is more complex
 	fee := pool.Fee
 	if fee == 0 {