Create an installation setup wizard

## Description

The current setup flow is not user-friendly and is intimidating to first time users. A setup wizard and/or installation script needs to be made so the user can start playing the game without any difficulty during installation.

## Steps to Implement

The setup wizard/installation script should do the following:
1. Download the required assets in a new folder preferably in the user home directory ( `~/cli-rpg/` ).
2. Add the executable to path.
3. Display a message upon successful installation to open a new terminal instance and run `cli-rpg`.

**Note:** Ensure that all potential error cases are handled appropriately, with no scenarios left unaddressed.

Start by inspecting the current setup flow, executable entry point, and asset-loading path to learn how installation works today. Compare that flow with the three requested outcomes: downloading assets to ~/cli-rpg/, adding the executable to PATH, and reporting successful completion; done means those steps work and installation errors are handled.

Written by the indexing model from the issue text.