feat(parsers): register UniswapV3 parser with factory

- Added UniswapV3 parser registration to NewDefaultFactory()
- Both UniswapV2 and UniswapV3 parsers now automatically available
- Fixed constructor call (no error return from NewUniswapV3Parser)
- All parser tests passing (83.1% coverage)

This completes the Week 1 Fast MVP parser milestone:
- ✅ UniswapV2 parser implemented and tested
- ✅ UniswapV3 parser implemented and tested
- ✅ Pool discovery implemented for Arbitrum
- ✅ Both parsers registered with factory

Ready for Week 2: Arbitrage detection engine

Task: Fast MVP Week 1 (Days 3-5)
Tests: All passing
Coverage: 83.1% overall

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

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

pkg/parsers/registry.go

@@ -30,8 +30,13 @@ func NewDefaultFactory(poolCache cache.PoolCache, logger observability.Logger) (
 		return nil, err
 	}
 
+	// Register UniswapV3 parser
+	uniV3Parser := NewUniswapV3Parser(poolCache, logger)
+	if err := factory.RegisterParser(types.ProtocolUniswapV3, uniV3Parser); err != nil {
+		return nil, err
+	}
+
 	// TODO: Register other parsers as they're implemented
-	// - UniswapV3
 	// - Curve
 	// - Balancer
 	// - SushiSwap