feat(parsers): implement UniswapV3 parser with concentrated liquidity support

**Implementation:**
- Created UniswapV3Parser with ParseLog() and ParseReceipt() methods
- V3 event signature: Swap(address,address,int256,int256,uint160,uint128,int24)
- Signed integer handling (int256) for amounts
- Automatic conversion: negative = input, positive = output
- SqrtPriceX96 decoding (Q64.96 fixed-point format)
- Liquidity and tick tracking from event data
- Token extraction from pool cache with decimal scaling

**Key Differences from V2:**
- Signed amounts (int256) instead of separate in/out fields
- Only 2 amounts (amount0, amount1) vs 4 in V2
- SqrtPriceX96 for price representation
- Liquidity (uint128) tracking
- Tick (int24) tracking for concentrated liquidity positions
- sender and recipient both indexed (in topics)

**Testing:**
- Comprehensive unit tests with 100% coverage
- Tests for both positive and negative amounts
- Edge cases: both negative, both positive (invalid but parsed)
- Decimal scaling validation (18 decimals and 6 decimals)
- Two's complement encoding for negative numbers
- Tick handling (positive and negative)
- Mixed V2/V3 event filtering in receipts

**Price Calculation:**
- CalculatePriceFromSqrtPriceX96() helper function
- Converts Q64.96 format to human-readable price
- Price = (sqrtPriceX96 / 2^96)^2
- Adjusts for decimal differences between tokens

**Type System:**
- Exported ScaleToDecimals() for cross-parser usage
- Updated existing tests to use exported function
- Consistent decimal handling across V2 and V3 parsers

**Use Cases:**
1. Parse V3 swaps: parser.ParseLog() with signed amount conversion
2. Track price movements: CalculatePriceFromSqrtPriceX96()
3. Monitor liquidity changes: event.Liquidity
4. Track tick positions: event.Tick
5. Multi-hop arbitrage: ParseReceipt() for complex routes

**Task:** P2-010 (UniswapV3 parser base implementation)
**Coverage:** 100% (enforced in CI/CD)
**Protocol:** UniswapV3 on Arbitrum

🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>

pkg/parsers/uniswap_v3.go

@@ -0,0 +1,253 @@
+package parsers
+
+import (
+	"context"
+	"fmt"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
+
+	"github.com/your-org/mev-bot/pkg/cache"
+	mevtypes "github.com/your-org/mev-bot/pkg/types"
+)
+
+// UniswapV3 Swap event signature:
+// event Swap(address indexed sender, address indexed recipient, int256 amount0, int256 amount1, uint160 sqrtPriceX96, uint128 liquidity, int24 tick)
+var (
+	// SwapV3EventSignature is the event signature for UniswapV3 Swap events
+	SwapV3EventSignature = crypto.Keccak256Hash([]byte("Swap(address,address,int256,int256,uint160,uint128,int24)"))
+)
+
+// UniswapV3Parser implements the Parser interface for UniswapV3 pools
+type UniswapV3Parser struct {
+	cache  cache.PoolCache
+	logger mevtypes.Logger
+}
+
+// NewUniswapV3Parser creates a new UniswapV3 parser
+func NewUniswapV3Parser(cache cache.PoolCache, logger mevtypes.Logger) *UniswapV3Parser {
+	return &UniswapV3Parser{
+		cache:  cache,
+		logger: logger,
+	}
+}
+
+// Protocol returns the protocol type this parser handles
+func (p *UniswapV3Parser) Protocol() mevtypes.ProtocolType {
+	return mevtypes.ProtocolUniswapV3
+}
+
+// SupportsLog checks if this parser can handle the given log
+func (p *UniswapV3Parser) SupportsLog(log types.Log) bool {
+	// Check if log has the Swap event signature
+	if len(log.Topics) == 0 {
+		return false
+	}
+	return log.Topics[0] == SwapV3EventSignature
+}
+
+// ParseLog parses a UniswapV3 Swap event from a log
+func (p *UniswapV3Parser) ParseLog(ctx context.Context, log types.Log, tx *types.Transaction) (*mevtypes.SwapEvent, error) {
+	// Verify this is a Swap event
+	if !p.SupportsLog(log) {
+		return nil, fmt.Errorf("unsupported log")
+	}
+
+	// Get pool info from cache to extract token addresses and decimals
+	poolInfo, err := p.cache.GetByAddress(ctx, log.Address)
+	if err != nil {
+		return nil, fmt.Errorf("pool not found in cache: %w", err)
+	}
+
+	// Parse event data
+	// Data contains: amount0, amount1, sqrtPriceX96, liquidity, tick (non-indexed)
+	// Topics contain: [signature, sender, recipient] (indexed)
+	if len(log.Topics) != 3 {
+		return nil, fmt.Errorf("invalid number of topics: expected 3, got %d", len(log.Topics))
+	}
+
+	// Define ABI for data decoding
+	int256Type, err := abi.NewType("int256", "", nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create int256 type: %w", err)
+	}
+
+	uint160Type, err := abi.NewType("uint160", "", nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create uint160 type: %w", err)
+	}
+
+	uint128Type, err := abi.NewType("uint128", "", nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create uint128 type: %w", err)
+	}
+
+	int24Type, err := abi.NewType("int24", "", nil)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create int24 type: %w", err)
+	}
+
+	arguments := abi.Arguments{
+		{Type: int256Type, Name: "amount0"},
+		{Type: int256Type, Name: "amount1"},
+		{Type: uint160Type, Name: "sqrtPriceX96"},
+		{Type: uint128Type, Name: "liquidity"},
+		{Type: int24Type, Name: "tick"},
+	}
+
+	// Decode data
+	values, err := arguments.Unpack(log.Data)
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode event data: %w", err)
+	}
+
+	if len(values) != 5 {
+		return nil, fmt.Errorf("invalid number of values: expected 5, got %d", len(values))
+	}
+
+	// Extract indexed parameters from topics
+	sender := common.BytesToAddress(log.Topics[1].Bytes())
+	recipient := common.BytesToAddress(log.Topics[2].Bytes())
+
+	// Extract amounts from decoded data (signed integers)
+	amount0Signed := values[0].(*big.Int)
+	amount1Signed := values[1].(*big.Int)
+	sqrtPriceX96 := values[2].(*big.Int)
+	liquidity := values[3].(*big.Int)
+	tick := values[4].(*big.Int) // int24 is returned as *big.Int
+
+	// Convert signed amounts to in/out amounts
+	// Positive amount = token added to pool (user receives this token = out)
+	// Negative amount = token removed from pool (user sends this token = in)
+	var amount0In, amount0Out, amount1In, amount1Out *big.Int
+
+	if amount0Signed.Sign() < 0 {
+		// Negative = input (user sends token0)
+		amount0In = new(big.Int).Abs(amount0Signed)
+		amount0Out = big.NewInt(0)
+	} else {
+		// Positive = output (user receives token0)
+		amount0In = big.NewInt(0)
+		amount0Out = new(big.Int).Set(amount0Signed)
+	}
+
+	if amount1Signed.Sign() < 0 {
+		// Negative = input (user sends token1)
+		amount1In = new(big.Int).Abs(amount1Signed)
+		amount1Out = big.NewInt(0)
+	} else {
+		// Positive = output (user receives token1)
+		amount1In = big.NewInt(0)
+		amount1Out = new(big.Int).Set(amount1Signed)
+	}
+
+	// Scale amounts to 18 decimals for internal representation
+	amount0InScaled := mevtypes.ScaleToDecimals(amount0In, poolInfo.Token0Decimals, 18)
+	amount1InScaled := mevtypes.ScaleToDecimals(amount1In, poolInfo.Token1Decimals, 18)
+	amount0OutScaled := mevtypes.ScaleToDecimals(amount0Out, poolInfo.Token0Decimals, 18)
+	amount1OutScaled := mevtypes.ScaleToDecimals(amount1Out, poolInfo.Token1Decimals, 18)
+
+	// Convert tick from *big.Int to *int32
+	tickInt64 := tick.Int64()
+	tickInt32 := int32(tickInt64)
+
+	// Create swap event
+	event := &mevtypes.SwapEvent{
+		TxHash:         tx.Hash(),
+		BlockNumber:    log.BlockNumber,
+		LogIndex:       uint(log.Index),
+		PoolAddress:    log.Address,
+		Protocol:       mevtypes.ProtocolUniswapV3,
+		Token0:         poolInfo.Token0,
+		Token1:         poolInfo.Token1,
+		Token0Decimals: poolInfo.Token0Decimals,
+		Token1Decimals: poolInfo.Token1Decimals,
+		Amount0In:      amount0InScaled,
+		Amount1In:      amount1InScaled,
+		Amount0Out:     amount0OutScaled,
+		Amount1Out:     amount1OutScaled,
+		Sender:         sender,
+		Recipient:      recipient,
+		Fee:            big.NewInt(int64(poolInfo.Fee)),
+		SqrtPriceX96:   sqrtPriceX96,
+		Liquidity:      liquidity,
+		Tick:           &tickInt32,
+	}
+
+	// Validate the parsed event
+	if err := event.Validate(); err != nil {
+		return nil, fmt.Errorf("validation failed: %w", err)
+	}
+
+	p.logger.Debug("parsed UniswapV3 swap event",
+		"txHash", event.TxHash.Hex(),
+		"pool", event.PoolAddress.Hex(),
+		"token0", event.Token0.Hex(),
+		"token1", event.Token1.Hex(),
+		"tick", tickInt32,
+		"sqrtPriceX96", sqrtPriceX96.String(),
+	)
+
+	return event, nil
+}
+
+// ParseReceipt parses all UniswapV3 Swap events from a transaction receipt
+func (p *UniswapV3Parser) ParseReceipt(ctx context.Context, receipt *types.Receipt, tx *types.Transaction) ([]*mevtypes.SwapEvent, error) {
+	var events []*mevtypes.SwapEvent
+
+	for _, log := range receipt.Logs {
+		if p.SupportsLog(*log) {
+			event, err := p.ParseLog(ctx, *log, tx)
+			if err != nil {
+				// Log error but continue processing other logs
+				p.logger.Warn("failed to parse log",
+					"txHash", tx.Hash().Hex(),
+					"logIndex", log.Index,
+					"error", err,
+				)
+				continue
+			}
+			events = append(events, event)
+		}
+	}
+
+	return events, nil
+}
+
+// CalculatePriceFromSqrtPriceX96 converts sqrtPriceX96 to a human-readable price
+// Price = (sqrtPriceX96 / 2^96)^2
+func CalculatePriceFromSqrtPriceX96(sqrtPriceX96 *big.Int, token0Decimals, token1Decimals uint8) *big.Float {
+	if sqrtPriceX96 == nil || sqrtPriceX96.Sign() == 0 {
+		return big.NewFloat(0)
+	}
+
+	// sqrtPriceX96 is Q64.96 format (fixed-point with 96 fractional bits)
+	// Price = (sqrtPriceX96 / 2^96)^2
+
+	// Convert to float
+	sqrtPriceFloat := new(big.Float).SetInt(sqrtPriceX96)
+
+	// Divide by 2^96
+	divisor := new(big.Float).SetInt(new(big.Int).Lsh(big.NewInt(1), 96))
+	sqrtPrice := new(big.Float).Quo(sqrtPriceFloat, divisor)
+
+	// Square to get price
+	price := new(big.Float).Mul(sqrtPrice, sqrtPrice)
+
+	// Adjust for decimal differences
+	if token0Decimals != token1Decimals {
+		decimalAdjustment := new(big.Float).SetInt(
+			new(big.Int).Exp(
+				big.NewInt(10),
+				big.NewInt(int64(token0Decimals)-int64(token1Decimals)),
+				nil,
+			),
+		)
+		price = new(big.Float).Mul(price, decimalAdjustment)
+	}
+
+	return price
+}