🚨 Critical Issue #76: SocketBox Method Call Deadlock Investigation

## 🎯 Problem Identification Complete
- SocketBox method calls (bind, isServer, toString) cause infinite blocking
- Root cause: Method resolution pipeline deadlock before execute_socket_method
- Other Box types (ArrayBox, StringBox, MapBox) work normally
- Arc<Mutex> reference sharing confirmed working (Arc addresses match = true)

## 🔧 Debug Infrastructure Added
- Comprehensive debug logging in socket_box.rs (bind, isServer, clone, toString)
- Method call tracing in http_methods.rs
- Deadlock detection points identified at interpreter expressions.rs:462-464

## 📋 Issue #76 Created for Copilot Investigation
- Systematic root cause analysis requirements (Architecture→Parser→Runtime levels)
- Comprehensive test cases: minimal/comprehensive/comparison scenarios
- Strict prohibition of band-aid fixes - architectural analysis required
- Hypothesis: Multiple Arc<Mutex> combinations causing circular deadlock

## 🧪 Test Suite Added
- test_socket_deadlock_minimal.nyash: Minimal reproduction case
- test_socket_methods_comprehensive.nyash: All methods deadlock verification
- test_other_boxes_working.nyash: Normal Box operation confirmation
- SOCKETBOX_ISSUE_REPRODUCTION.md: Complete reproduction guide

## 📊 Impact Assessment
- Phase 9 HTTP server implementation completely blocked
- SocketBox functionality entirely non-functional
- Critical blocker for production readiness
- Requires immediate systematic investigation

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

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

src/interpreter/objects.rs

@@ -9,6 +9,7 @@
 use super::*;
 use crate::boxes::{NullBox, ConsoleBox, FloatBox, DateTimeBox, SocketBox, HTTPServerBox, HTTPRequestBox, HTTPResponseBox};
 // use crate::boxes::intent_box_wrapper::IntentBoxWrapper;
+use crate::box_trait::SharedNyashBox;
 use std::sync::Arc;
 
 impl NyashInterpreter {
@@ -708,6 +709,9 @@ impl NyashInterpreter {
         // 現在のスコープでBoxを追跡（自動解放のため）
         // 🌍 革命的実装：Environment tracking廃止
         
+        // Create Arc outside if block so it's available in all scopes
+        let instance_arc = Arc::from(instance_box);
+        
         // コンストラクタを呼び出す
         // "pack/引数数"、"init/引数数"、"Box名/引数数" の順で試す
         let pack_key = format!("pack/{}", arguments.len());
@@ -718,7 +722,6 @@ impl NyashInterpreter {
             .or_else(|| final_box_decl.constructors.get(&init_key))
             .or_else(|| final_box_decl.constructors.get(&box_name_key)) {
             // コンストラクタを実行
-            let instance_arc = Arc::from(instance_box);
             self.execute_constructor(&instance_arc, constructor, arguments, &final_box_decl)?;
         } else if !arguments.is_empty() {
             return Err(RuntimeError::InvalidOperation {