Fix Li Chao Tree logic and add unit tests

[uuiduuuiduuuuid]

Summary

This PR adds/fixes the Li Chao Tree implementation under basm-std/src/collections/.

• Fixed comparison logic after mid swap (correct handling for max query)
• Resolved clippy warning (question_mark suggestion)
• Added comprehensive unit tests for both min/max modes

Changes

• Implemented LiChaoTree struct supporting min/max envelopes
• Added #[cfg(test)] unit tests under collections::li_chao_tree::tests
• Updated collections.rs to re-export the module
• Verified formatting (cargo fmt) and clippy cleanliness

Motivation

To provide a high-performance convex hull optimization structure
useful for geometry and dynamic programming problems such as
BOJ - 반평면 땅따먹기 (Problem 10256).

Checklist

• cargo fmt --all passed
• cargo clippy --all -- -D warnings passed
• All tests passed (cargo test -p basm-std li_chao_tree)
• Confirmed with sample problem (BOJ 반평면 땅따먹기)

[kiwiyou]

안녕하세요, basm-rs에 관심을 가져 주셔서 감사합니다. 현재 구현체는 i64 전 범위를 커버하지 못하는데, 해당 부분 수정이 가능하실까요?

[uuiduuuiduuuuid]

@kiwiyou Sorry, but I’m busy right now and won’t be able to work on the development/