Add --version flag to display version information

## Description

Add a --version or -v flag to display version information about nm-hotspot-cli.

## Desired behavior
\\\ash
nm-hotspot --version
nm-hotspot-cli v1.0.0

nm-hotspot -v
nm-hotspot-cli v1.0.0
\\\

## Implementation hints
- Add version constant at the top of the script
- Handle --version/-v flags in the main function
- Display version and exit

## Difficulty
Easy - Good first issue