Fix GetMerkleProof for odd numbered nodes

[galt-tr]

This pull request improves the handling of Merkle proofs for trees with an odd number of leaves, ensuring correct behavior and preventing potential panics when a leaf node does not have a sibling. It also adds comprehensive tests to verify this behavior and updates dependencies.

Merkle proof logic improvements

• Updated the getLeafSiblingHash function in subtree.go to correctly handle cases where a leaf node has no sibling by duplicating the last node's hash, following Bitcoin convention. This prevents panics when generating proofs for odd numbers of leaves.

Testing enhancements

• Added TestGetMerkleProofOddLeaves in subtree_test.go with multiple sub-tests to verify Merkle proof correctness for trees with odd and even numbers of leaves, including large trees. These tests ensure the new logic works as intended and prevent regressions.

Dependency updates

• Updated the Go version in go.mod from 1.24.3 to 1.24.6 and bumped the golang.org/x/exp dependency to a newer version.

[github-actions]

👋 Thanks, @galt-tr!

This pull request comes from a fork. For security, our CI runs in a restricted mode.
A maintainer will triage this shortly and run any additional checks as needed.

• 🏷️ Labeled: fork-pr, requires-manual-review
• 👀 We'll review and follow up here if anything else is needed.

Thanks for contributing to bsv-blockchain/go-subtree! 🚀

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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