feat: add Rust solution for lc No.1339

[yanglbme]

No description provided.

[Copilot]

Pull request overview

This PR adds a Rust solution implementation for LeetCode problem 1339 (Maximum Product of Splitted Binary Tree) and updates the C++ solution to use modern lambda syntax. The changes include adding the Rust code file and documenting it in both English and Chinese README files, along with updating the algorithm description and modernizing the C++ implementation.

• Added complete Rust solution with helper methods for calculating tree sums and finding maximum product
• Updated C++ lambda syntax from function<> to modern auto with explicit this capture
• Enhanced documentation with detailed algorithm explanation

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
Solution.rs	New Rust implementation using two DFS traversals to solve the maximum product problem
Solution.cpp	Modernized lambda function declarations using C++23 explicit object parameter syntax
README_EN.md	Added algorithm description and Rust code example to English documentation
README.md	Added algorithm description and Rust code example to Chinese documentation

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