feat(command): add help command

app/src/main/kotlin/app/AppInitializer.kt

@@ -4,19 +4,21 @@ import command.CommandManager
 import command.commands.Add
 import command.commands.Clear
 import command.commands.Exit
+import command.commands.Help
 import io.IOHandler
 import manager.CollectionManager
 
 class AppInitializer {
     fun setup(
-        manager: CommandManager,
+        commandManager: CommandManager,
         io: IOHandler,
         app: AppExecutor,
     ) {
         val collectionManager = CollectionManager(io)
 
-        manager.register(Add(io, collectionManager))
-        manager.register(Exit(io) { app.stop() })
-        manager.register(Clear(io, collectionManager))
+        commandManager.register(Add(io, collectionManager))
+        commandManager.register(Exit(io) { app.stop() })
+        commandManager.register(Clear(io, collectionManager))
+        commandManager.register(Help(io, commandManager))
     }
 }

app/src/main/kotlin/command/CommandManager.kt

@@ -21,4 +21,6 @@ class CommandManager {
             io.println("команда не найдена")
         }
     }
+
+    fun getCommands() = commands
 }

app/src/main/kotlin/command/commands/Help.kt

@@ -0,0 +1,19 @@
+package command.commands
+
+import command.Command
+import command.CommandManager
+import io.IOHandler
+
+class Help(
+    private val io: IOHandler,
+    private val commandManager: CommandManager,
+) : Command {
+    override val name = "help"
+    override val description = "show avaliable commands"
+
+    override fun execute() {
+        for (command in commandManager.getCommands().values) {
+            io.println("${command.name}: ${command.description}")
+        }
+    }
+}