refactor: replace custom proc-macro with strum for snake_case serialization

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/lib.rs

@@ -14,8 +14,5 @@ pub use args::Args;
 // Re-export PIPESIZE constant
 pub use common::PIPESIZE;
 
-// Re-export the ToSnakeCaseString trait and derive macro
-pub use to_snake_case_trait::ToSnakeCaseString;
-
 #[cfg(test)]
 mod tests;