v0.1.0 of envault_cli

Standalone CLI code generator for the envault package. Encrypts your .env file into a secure dart vault using AES-256-GCM. Changelog excerpt: - Initial release of envault_cli. - Fast, standalone CLI generator (no build_runnerrequired). - Extracts .env, checks entropy/placeholders via envault validate. - Emits securely encrypted vault.g.dartusing AES-256-GCM.