Module config/schema

Configuration schema types for igcv3. Defines the structure of igcv3.conf.yml configuration file.

Configuration is loaded via cascade (highest priority last):

1. Internal defaults (hardcoded in defaults.ts)
2. System config (/etc/igcv3/igcv3.conf.yml - Linux/macOS only)
3. User config (~/.config/igcv3/igcv3.conf.yml)
4. Local config (./igcv3.conf.yml in current directory)
5. Custom config (--config CLI option)

Each layer overrides values from previous layers via deep merge.