🔧 refactor: すべてのBoxをArc<Mutex>パターンで統一

CopilotのBox実装を私たちのArc<Mutex>パターンで統一：
- BufferBox: Arc<Mutex<Vec<u8>>>で内部可変性を実現
- FileBox: Arc<Mutex<File>>でファイルハンドル管理
- JSONBox: Arc<Mutex<Value>>でJSON値を保持
- HttpClientBox: Arc<Mutex<Client>>でHTTPクライアント管理
- StreamBox: Arc<Mutex>でストリームバッファと位置を管理
- RegexBox: Arc<Regex>で軽量ラッパー実装

各Boxに実用的なメソッドも追加：
- BufferBox: write, read, readAll, clear, length, append, slice
- FileBox: read, write, exists, delete, copy
- JSONBox: parse, stringify, get, set, has, keys
- HttpClientBox: get, post, put, delete, request
- StreamBox: write, read, position, length, reset
- RegexBox: test, find, findAll, replace, split

interpreterに新Box用のメソッド実行を追加：
- data_methods.rs: BufferBox, JSONBox, RegexBox
- network_methods.rs: HttpClientBox, StreamBox

これでコードベース全体が一貫性のあるArc<Mutex>パターンで統一されました！

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

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

src/interpreter/methods/network_methods.rs

@@ -0,0 +1,124 @@
+/*!
+ * Network and Communication Box Methods Module
+ * 
+ * Contains method implementations for network-related Box types:
+ * - HttpClientBox (execute_http_method) - HTTP client operations
+ * - StreamBox (execute_stream_method) - Stream processing operations
+ */
+
+use super::super::*;
+use crate::box_trait::{NyashBox, StringBox};
+use crate::boxes::{HttpClientBox, StreamBox};
+
+impl NyashInterpreter {
+    /// HttpClientBoxのメソッド呼び出しを実行
+    pub(in crate::interpreter) fn execute_http_method(&mut self, http_box: &HttpClientBox, method: &str, arguments: &[ASTNode]) 
+        -> Result<Box<dyn NyashBox>, RuntimeError> {
+        match method {
+            "get" => {
+                if arguments.len() != 1 {
+                    return Err(RuntimeError::InvalidOperation {
+                        message: format!("get() expects 1 argument, got {}", arguments.len()),
+                    });
+                }
+                let url = self.execute_expression(&arguments[0])?;
+                Ok(http_box.http_get(url))
+            }
+            "post" => {
+                if arguments.len() != 2 {
+                    return Err(RuntimeError::InvalidOperation {
+                        message: format!("post() expects 2 arguments, got {}", arguments.len()),
+                    });
+                }
+                let url = self.execute_expression(&arguments[0])?;
+                let body = self.execute_expression(&arguments[1])?;
+                Ok(http_box.post(url, body))
+            }
+            "put" => {
+                if arguments.len() != 2 {
+                    return Err(RuntimeError::InvalidOperation {
+                        message: format!("put() expects 2 arguments, got {}", arguments.len()),
+                    });
+                }
+                let url = self.execute_expression(&arguments[0])?;
+                let body = self.execute_expression(&arguments[1])?;
+                Ok(http_box.put(url, body))
+            }
+            "delete" => {
+                if arguments.len() != 1 {
+                    return Err(RuntimeError::InvalidOperation {
+                        message: format!("delete() expects 1 argument, got {}", arguments.len()),
+                    });
+                }
+                let url = self.execute_expression(&arguments[0])?;
+                Ok(http_box.delete(url))
+            }
+            "request" => {
+                if arguments.len() != 3 {
+                    return Err(RuntimeError::InvalidOperation {
+                        message: format!("request() expects 3 arguments, got {}", arguments.len()),
+                    });
+                }
+                let method_arg = self.execute_expression(&arguments[0])?;
+                let url = self.execute_expression(&arguments[1])?;
+                let options = self.execute_expression(&arguments[2])?;
+                Ok(http_box.request(method_arg, url, options))
+            }
+            _ => Err(RuntimeError::InvalidOperation {
+                message: format!("Unknown method '{}' for HttpClientBox", method),
+            })
+        }
+    }
+
+    /// StreamBoxのメソッド呼び出しを実行
+    pub(in crate::interpreter) fn execute_stream_method(&mut self, stream_box: &StreamBox, method: &str, arguments: &[ASTNode]) 
+        -> Result<Box<dyn NyashBox>, RuntimeError> {
+        match method {
+            "write" => {
+                if arguments.len() != 1 {
+                    return Err(RuntimeError::InvalidOperation {
+                        message: format!("write() expects 1 argument, got {}", arguments.len()),
+                    });
+                }
+                let data = self.execute_expression(&arguments[0])?;
+                Ok(stream_box.stream_write(data))
+            }
+            "read" => {
+                if arguments.len() != 1 {
+                    return Err(RuntimeError::InvalidOperation {
+                        message: format!("read() expects 1 argument, got {}", arguments.len()),
+                    });
+                }
+                let count = self.execute_expression(&arguments[0])?;
+                Ok(stream_box.stream_read(count))
+            }
+            "position" => {
+                if !arguments.is_empty() {
+                    return Err(RuntimeError::InvalidOperation {
+                        message: format!("position() expects 0 arguments, got {}", arguments.len()),
+                    });
+                }
+                Ok(stream_box.get_position())
+            }
+            "length" => {
+                if !arguments.is_empty() {
+                    return Err(RuntimeError::InvalidOperation {
+                        message: format!("length() expects 0 arguments, got {}", arguments.len()),
+                    });
+                }
+                Ok(stream_box.get_length())
+            }
+            "reset" => {
+                if !arguments.is_empty() {
+                    return Err(RuntimeError::InvalidOperation {
+                        message: format!("reset() expects 0 arguments, got {}", arguments.len()),
+                    });
+                }
+                Ok(stream_box.stream_reset())
+            }
+            _ => Err(RuntimeError::InvalidOperation {
+                message: format!("Unknown method '{}' for StreamBox", method),
+            })
+        }
+    }
+}