feat: Initial release

Initial release with bash-completion and API commands. Supports configuration
using CLI flags, environment variables, or YAML/JSON files.

- Initial project boilerplate (docs, license, contributing, etc)
- Bash completion is via the `bash-completion` command

Added the following commands that interact with the Signal Sciences API:

- get-corp
- list-agents
- list-corps
- list-suspicious-ips
- list-top-attacks