feat: add solutions for lc No.3640

[yanglbme]

No description provided.

[Copilot]

Pull request overview

This PR adds solution implementations for LeetCode problem 3640 "Trionic Array II" from Weekly Contest 461 Q4. The problem requires finding the maximum sum of a "trionic subarray" - a contiguous subarray with three parts: strictly increasing, strictly decreasing, then strictly increasing again.

Changes:

• Added complete solution implementations in 6 languages (Python, Java, C++, Go, Rust, TypeScript)
• Added comprehensive documentation in both Chinese (README.md) and English (README_EN.md)
• Updated contest registry files to include the new problem

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
solution/3600-3699/3640.Trionic Array II/README.md	Chinese problem description, solution explanation, and code examples
solution/3600-3699/3640.Trionic Array II/README_EN.md	English problem description, solution explanation, and code examples
solution/3600-3699/3640.Trionic Array II/Solution.py	Python implementation using grouped loop algorithm
solution/3600-3699/3640.Trionic Array II/Solution.java	Java implementation with proper long type handling
solution/3600-3699/3640.Trionic Array II/Solution.cpp	C++ implementation with LLONG_MIN initialization
solution/3600-3699/3640.Trionic Array II/Solution.go	Go implementation with int64 type conversions
solution/3600-3699/3640.Trionic Array II/Solution.rs	Rust implementation with i64 type and proper casting
solution/3600-3699/3640.Trionic Array II/Solution.ts	TypeScript implementation with -Infinity initialization
solution/CONTEST_README.md	Added problem entry to contest 461 listing
solution/CONTEST_README_EN.md	Added problem entry to English contest 461 listing
solution/README.md	Added problem entry to main problem index
solution/README_EN.md	Added problem entry to English problem index

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