Feature: Save/load favorites (persisted JSON)

[wiertmir]

Goal

Allow users to "star" favorite monkeys and persist favorites across runs (simple JSON file in user config).

Why

Keeps users engaged and showcases basic persistence.

Light implementation notes

• Create Helpers/FavoritesHelper.cs with methods LoadFavorites(), SaveFavorites(IEnumerable<string> favoriteNames), ToggleFavorite(string name).
• Use Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) on Windows or XDG fallback on Linux/macOS to create MyMonkeyApp folder and favorites.json file.
• Persist a JSON array of monkey names using System.Text.Json.
• Extend Program.cs menu with option to list favorites and toggle a favorite while viewing details.
• Add tests for save/load roundtrip using a temp directory override.

Files to modify/create

• MyMonkeyApp/Helpers/FavoritesHelper.cs
• MyMonkeyApp/Program.cs (menu additions)

Labels:["enhancement","feature-request","good first issue","area-console"]