feature: implemented and tested rename command

src/main/java/com/mycmd/App.java

@@ -103,6 +103,7 @@ private static void registerCommands(Map<String, Command> commands) {
         commands.put("ipconfig", new IpConfig());
         commands.put("alias", new AliasCommand());
         commands.put("unalias", new UnaliasCommand());
+        commands.put("rename", new RenameCommand());
         commands.put("tasklist", new TasklistCommand());
     }
 }

src/main/java/com/mycmd/commands/RenameCommand.java

@@ -0,0 +1,49 @@
+package com.mycmd.commands;
+
+import com.mycmd.Command;
+import com.mycmd.ShellContext;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.StandardCopyOption;
+
+/**
+ * Implements the "rename" (or "ren") command for MyCMD.
+ * Usage: rename <oldName> <newName>
+ */
+public class RenameCommand implements Command {
+
+    @Override
+    public void execute(String[] args, ShellContext context) throws IOException {
+        if (args.length != 2) {
+            System.out.println("Usage: " + usage());
+            return;
+        }
+
+        File oldFile = context.resolvePath(args[0]);
+        File newFile = context.resolvePath(args[1]);
+
+        if (!oldFile.exists()) {
+            System.out.println("The system cannot find the file specified: " + args[0]);
+            return;
+        }
+
+        try {
+            Files.move(oldFile.toPath(), newFile.toPath(), StandardCopyOption.REPLACE_EXISTING);
+            System.out.println("File renamed from " + oldFile.getName() + " to " + newFile.getName());
+        } catch (IOException e) {
+            throw new IOException("Failed to rename file: " + e.getMessage(), e);
+        }
+    }
+
+    @Override
+    public String description() {
+        return "Renames a file or directory.";
+    }
+
+    @Override
+    public String usage() {
+        return "rename <oldName> <newName>";
+    }
+}