🚨 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_minimal_socket.nyash

@@ -0,0 +1,31 @@
+# 🔥 最小限SocketBoxテスト - bind()のみ
+
+static box Main {
+    init { console }
+    
+    main() {
+        me.console = new ConsoleBox()
+        me.console.log("最小限SocketBoxテスト開始")
+        
+        # SocketBox作成
+        local socket = new SocketBox()
+        me.console.log("SocketBox作成完了")
+        
+        # bind前状態
+        local beforeBind = socket.isServer()
+        me.console.log("Before: " + beforeBind.toString())
+        
+        # bind実行
+        local bindResult = socket.bind("127.0.0.1", 19999)
+        me.console.log("Bind: " + bindResult.toString())
+        
+        # bind後状態
+        local afterBind = socket.isServer()
+        me.console.log("After: " + afterBind.toString())
+        
+        # クリーンアップ
+        socket.close()
+        
+        return "DONE"
+    }
+}