Add version reporting to the CLI

[berggren]

Summary

Introduced a version variable and integrated it into the root command to enable version reporting in the CLI.

Technical Details:

• Version Definition: Created internal/cli/version.go to hold a global Version string. The variable defaults to "dev" but is designed to be overwritten during the build process using -ldflags.
• Cobra Integration: Updated the NewRootCmd configuration in internal/cli/cli.go to include the Version property. This enables the CLI to automatically handle --version and -v flags, providing users with the current build version.