🚨 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>

test_socket_bind_only.nyash

@@ -0,0 +1,34 @@
+# 🔥 SocketBox bind()のみテスト - toString()なし
+
+static box Main {
+    init { console, result }
+    
+    main() {
+        me.console = new ConsoleBox()
+        me.console.log("SocketBox bind()テスト開始")
+        
+        # SocketBox作成
+        local socket = new SocketBox()
+        me.console.log("SocketBox作成完了")
+        
+        # bind実行（toString()やisServer()を避ける）
+        me.console.log("bind実行開始...")
+        local bindResult = socket.bind("127.0.0.1", 19999)
+        me.console.log("bind実行完了")
+        
+        # bindResultの状態だけ確認
+        if bindResult.equals(true) {
+            me.result = "BIND_SUCCESS"
+            me.console.log("bind成功!")
+        } else {
+            me.result = "BIND_FAILED"
+            me.console.log("bind失敗!")
+        }
+        
+        # クリーンアップ
+        socket.close()
+        me.console.log("テスト完了")
+        
+        return me.result
+    }
+}