- Add token CLI subcommand with export/import operations
- Enable OAuth2 token persistence across clean environments
- Support for containers, CI/CD, and ephemeral compute workflows
- Compress tokens with gzip and encode as base64 for env vars
- Automatic token restoration from CULL_GMAIL_TOKEN_CACHE
- Secure file permissions (600) on restored tokens
- Add comprehensive error handling for token operations
- Update dependencies: base64, flate2, serde_json
This feature enables cull-gmail to run in ephemeral environments
like Docker containers and CI/CD pipelines without re-authentication
by exporting tokens once and restoring them via environment variables.
- load configuration from a file
- use config crate for config loading
- allow overriding config with environment variables
- set default credential path
- fix error handling for config loading
- introduce `NoRuleSelector`, `NoRuleFoundForLabel`, and `LabelNotFoundInRules` errors
- these errors provide more specific feedback when rule selection fails
- add specific error variants for unset directory, home expansion failure, and directory creation failure
- improve error reporting by providing more context in error messages
