Implement size-based method to distinguish child tree from thread in AVL balanced trees

[konard]

🎯 Summary

This PR implements a different approach to distinguish between child tree and thread relationships in AVL balanced trees, as requested in issue #86.

🔄 Changes Made

Instead of using bitwise operations on packed values, the new implementation uses size comparison which is more intuitive and aligns with the natural properties of AVL trees where a parent's subtree size is always larger than its children's subtree sizes.

Key Changes:

1. Added new methods in LinksAvlBalancedTreeMethodsBase.cs:

   • GetLeftIsChildBySizeComparison(TLinkAddress node)
   • GetRightIsChildBySizeComparison(TLinkAddress node)

2. Modified concrete implementations to use size-based comparison:

   • LinksTargetsAvlBalancedTreeMethods.cs - Updated GetLeftIsChild and GetRightIsChild methods
   • LinksSourcesAvlBalancedTreeMethods.cs - Updated GetLeftIsChild and GetRightIsChild methods

Implementation Logic:

The new approach uses the following logic:

// For left child detection
var nodeSize = GetSize(node);
var left = GetLeft(node);
var leftSize = GetSizeOrZero(left);
return leftSize > TLinkAddress.Zero && nodeSize > leftSize;

// For right child detection  
var nodeSize = GetSize(node);
var right = GetRight(node);
var rightSize = GetSizeOrZero(right);
return rightSize > TLinkAddress.Zero && nodeSize > rightSize;

This replaces the previous bitwise operations:

// Old approach
return _addressToBoolConverter.Convert(source: Bit<TLinkAddress>.PartialRead(target: value, shift: 4, limit: 1));

✅ Testing

• ✅ Project builds successfully without compilation errors
• ✅ All existing tests pass
• ✅ No regressions detected
• ✅ Maintains backward compatibility

💡 Benefits

1. More Intuitive: Uses natural AVL tree properties instead of bit manipulation
2. Readable: The logic is self-documenting and easier to understand
3. Maintainable: Reduces complexity compared to bitwise operations
4. Correct: Leverages the fundamental property that parent nodes always have larger subtree sizes than their children

🔗 Related

• Fixes Attempt to use different way to distinguish between child tree and thread #86
• Addresses the TODO comments in the original codebase that suggested exploring size-based comparison

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