fix(arbitrage): critical fixes for struct initialization and price impact calculations

- Triangular arbitrage: populate all 25+ ArbitrageOpportunity fields
- Direct arbitrage: complete field initialization with gas cost calculation
- Price impact: add division-by-zero protection and validation
- Absolute value handling for swap amounts to prevent uint256 max display

Remaining issue: Some events still show uint256 max - needs investigation
of alternative parsing code path (possibly pkg/pools/discovery.go)

pkg/scanner/market/scanner.go

@@ -554,13 +554,33 @@ func (s *MarketScanner) findTriangularArbitrageOpportunities(event events.Event)
 				// Close the loop by adding the first token at the end
 				tokenPaths = append(tokenPaths, path.Tokens[0].Hex())
 
+				// Properly initialize all required fields
+				now := time.Now()
 				opportunity := stypes.ArbitrageOpportunity{
-					Path:        tokenPaths,
-					Pools:       []string{}, // Pool addresses will be discovered dynamically
-					Profit:      netProfit,
-					GasEstimate: gasEstimate,
-					ROI:         roi,
-					Protocol:    fmt.Sprintf("Triangular_%s", path.Name),
+					ID:              fmt.Sprintf("arb_%d_%s", now.Unix(), path.Tokens[0].Hex()[:10]),
+					Path:            tokenPaths,
+					Pools:           []string{}, // Pool addresses will be discovered dynamically
+					AmountIn:        testAmount,
+					Profit:          profit,
+					NetProfit:       netProfit,
+					GasEstimate:     gasEstimate,
+					GasCost:         gasEstimate, // Set gas cost same as estimate
+					EstimatedProfit: netProfit,
+					RequiredAmount:  testAmount,
+					ROI:             roi,
+					Protocol:        fmt.Sprintf("Triangular_%s", path.Name),
+					ExecutionTime:   500, // Estimated 500ms for triangular arb
+					Confidence:      0.5, // Medium confidence for triangular
+					PriceImpact:     0.0, // Will be calculated dynamically
+					MaxSlippage:     2.0, // 2% max slippage
+					TokenIn:         path.Tokens[0],
+					TokenOut:        path.Tokens[0], // Circular, starts and ends with same token
+					Timestamp:       now.Unix(),
+					DetectedAt:      now,
+					ExpiresAt:       now.Add(5 * time.Second), // 5 second expiry
+					Urgency:         5,                        // Medium urgency
+					Risk:            0.3,                      // Low-medium risk
+					Profitable:      netProfit.Sign() > 0,
 				}
 
 				opportunities = append(opportunities, opportunity)
@@ -1111,8 +1131,12 @@ func (s *MarketScanner) fetchPoolData(poolAddress string) (*CachedData, error) {
 		LastUpdated:  time.Now(),
 	}
 
+	liquidityStr := "0"
+	if poolState.Liquidity != nil {
+		liquidityStr = poolState.Liquidity.String()
+	}
 	s.logger.Info(fmt.Sprintf("Fetched real pool data for %s: Token0=%s, Token1=%s, Fee=%d, Liquidity=%s",
-		address.Hex(), poolState.Token0.Hex(), poolState.Token1.Hex(), poolState.Fee, poolState.Liquidity.String()))
+		address.Hex(), poolState.Token0.Hex(), poolState.Token1.Hex(), poolState.Fee, liquidityStr))
 
 	return poolData, nil
 }
@@ -1309,8 +1333,20 @@ func (s *MarketScanner) calculateUniswapV3Output(amountIn *big.Int, pool *Cached
 	// Subtract fee from output
 	finalAmountOut := new(big.Int).Sub(amountOut, feeAmount)
 
+	amountInStr := "0"
+	if amountIn != nil {
+		amountInStr = amountIn.String()
+	}
+	amountOutStr := "0"
+	if amountOut != nil {
+		amountOutStr = amountOut.String()
+	}
+	finalAmountOutStr := "0"
+	if finalAmountOut != nil {
+		finalAmountOutStr = finalAmountOut.String()
+	}
 	s.logger.Debug(fmt.Sprintf("V3 calculation: amountIn=%s, amountOut=%s, fee=%d, finalOut=%s",
-		amountIn.String(), amountOut.String(), fee, finalAmountOut.String()))
+		amountInStr, amountOutStr, fee, finalAmountOutStr))
 
 	return finalAmountOut, nil
 }