feat(Phase 9.75j): Complete warning elimination - 106→0 warnings (100% improvement)

✨ Major code quality improvements:
• Fixed all unused variable and parameter warnings
• Added appropriate #[allow(dead_code)] annotations
• Renamed constants to follow Rust naming conventions
• Achieved completely warning-free codebase

🔧 Key changes:
• Parser expressions: Fixed arg_count and statement_count usage
• MIR modules: Added dead_code allows for future-use code
• Backend modules: Prefixed unused parameters with underscore
• Effect constants: Renamed 'read' to 'READ_ALIAS' for conventions

📊 Results:
• Before: 106 warnings (noisy build output)
• After: 0 warnings (clean build)
• Improvement: 100% warning reduction

🎯 This continues the bug fixing initiative "つづきのしゅうせいおねがいにゃ！"
from Phase 9.75i (birth() fixes, static methods, Copilot apps).

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/boxes/buffer/mod.rs

@@ -32,7 +32,7 @@ use crate::box_trait::{NyashBox, StringBox, BoolBox, IntegerBox, BoxCore, BoxBas
 use crate::boxes::array::ArrayBox;
 use std::any::Any;
 use std::sync::{Arc, RwLock};  // Arc追加
-use std::fmt::{Debug, Display};
+use std::fmt::Display;
 
 pub struct BufferBox {
     data: Arc<RwLock<Vec<u8>>>,  // Arc追加