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/interpreter/core.rs

@@ -205,6 +205,7 @@ pub struct NyashInterpreter {
     pub(super) current_constructor_context: Option<ConstructorContext>,
     
     /// 🔄 評価スタック - 循環参照検出用
+    #[allow(dead_code)]
     pub(super) evaluation_stack: Vec<usize>,
     
     /// 🔗 Invalidated object IDs for weak reference system
@@ -411,7 +412,7 @@ impl NyashInterpreter {
                 eprintln!("🔍 DEBUG: nyashstd namespace found, checking static boxes...");
                 eprintln!("🔍 DEBUG: Available static boxes: {:?}", nyashstd_namespace.static_boxes.keys().collect::<Vec<_>>());
                 
-                if let Some(static_box) = nyashstd_namespace.static_boxes.get(name) {
+                if let Some(_static_box) = nyashstd_namespace.static_boxes.get(name) {
                     eprintln!("🔍 DEBUG: Found '{}' in nyashstd namespace", name);
                     
                     // BuiltinStaticBoxをInstanceBoxとしてラップ