Improve code readability

Enhance code clarity and maintainability by applying several readability techniques: extract repeated expressions into well-named variables, simplify complex boolean logic, use proper constant declarations, and remove redundant code that sets default values.

Key practices:

• Extract repeated expressions: When the same complex expression appears multiple times, extract it into a descriptive variable (e.g., mainAxisDim for node->getLayout().measuredDimensions[dim[mainAxis]])
• Simplify complex boolean expressions: Remove redundant parentheses and restructure logic for better visual parsing
• Use proper constant declarations: Prefer constexpr bool kConstantName = false; over preprocessor defines or global variables
• Remove redundant default assignments: Don’t explicitly set values that are already defaults (e.g., YGJustifyFlexStart is the default for justify content)

Example of extracting repeated expressions:

// Before
child->getLeadingPosition(mainAxis, node->getLayout().measuredDimensions[dim[mainAxis]])
child->getLeadingMargin(mainAxis, node->getLayout().measuredDimensions[dim[mainAxis]])

// After  
const auto mainAxisDim = node->getLayout().measuredDimensions[dim[mainAxis]];
child->getLeadingPosition(mainAxis, mainAxisDim)
child->getLeadingMargin(mainAxis, mainAxisDim)