Module color 

Color option handling for CLI.

Responsibilities:

• Define the ColorArg type for CLI argument parsing.
• Provide color initialization and global state management.

Not handled here:

• App-specific color handling (handled outside the CLI).
• Direct color output (see outpututil.rs and output/theme.rs).

Invariants/Assumptions:

• NO_COLOR environment variable takes precedence over CLI flags.
• Color initialization happens early in main() before any colored output.

Enums

ColorArg

Color output control options for CLI arguments.

Functions

init_color

Initialize colors from CLI arguments.