feat: add pwd command and fix bug in help command

Author: yuvii-b

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

@@ -77,5 +77,6 @@ private static void registerCommands(Map<String, Command> commands) {
         commands.put("tree", new TreeCommand());
         commands.put("date", new DateCommand());
         commands.put("history", new HistoryCommand());
+        commands.put("pwd", new PwdCommand());
     }
 }

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

@@ -20,8 +20,8 @@ public HelpCommand(Map<String, Command> commands) {
     @Override
     public void execute(String[] args, ShellContext context) {
         // Detailed help for a specific command
-        if (args.length > 1) {
-            String cmdName = args[1];
+        if (args.length > 0) {
+            String cmdName = args[0];
             Command cmd = commands.get(cmdName);
 
             if (cmd != null) {

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

@@ -0,0 +1,35 @@
+package com.mycmd.commands;
+
+import com.mycmd.Command;
+import com.mycmd.ShellContext;
+
+/**
+ * Prints the current working directory.
+ * 
+ * This command displays the absolute path of the current working directory
+ * stored in the shell context. It's equivalent to the Unix/Linux 'pwd' command
+ * and provides the same functionality as 'cd' without arguments.
+ * 
+ * Usage:
+ * - pwd : Print the current working directory path
+ * 
+ * The command always prints the absolute path of the current directory,
+ * making it useful for scripts and when you need to know your exact location
+ * in the file system.
+ */
+public class PwdCommand implements Command {
+    @Override
+    public void execute(String[] args, ShellContext context) {
+        System.out.println(context.getCurrentDir().getAbsolutePath());
+    }
+
+    @Override
+    public String description() {
+        return "Print the current working directory path.";
+    }
+
+    @Override
+    public String usage() {
+        return "pwd";
+    }
+}