getchar on non-terminal exit

[nihui]

No description provided.

[Copilot]

Pull Request Overview

This PR addresses graceful exit behavior by introducing a prompt for user key input when not running in an interactive terminal and modifying the command-line argument handling to allow running with no arguments.

• Added cross-platform terminal detection macros and corresponding includes
• Updated command-line argument validation to support both 0 and 1 device id argument
• Added a prompt on non-terminal exit using getchar()

[Copilot]

The usage message 'Usage: %s [device_id]' does not clearly convey that running the program with no arguments is valid. Consider updating the message to indicate that the device_id parameter is optional when no argument is provided.

Suggested change

	fprintf(stderr, "Usage: %s [device_id]\n", argv[0]);
	fprintf(stderr, "Usage: %s [device_id] (device_id is optional; defaults to the first available device if not provided)\n", argv[0]);