- Support 'secret unlockers add pgp [keyid]' positional argument syntax
- Automatically detect and use default GPG key when no key is specified
- Change PGP unlocker ID format from <keyid>-pgp to pgp-<keyid>
- Check if PGP key is already added before creating duplicate unlocker
- Add getDefaultGPGKey() that checks gpgconf first, then falls back to
first secret key
- Export ResolveGPGKeyFingerprint() for use in CLI
- Add checkUnlockerExists() helper to verify unlocker IDs
The new behavior:
- 'secret unlockers add pgp' uses default GPG key
- 'secret unlockers add pgp KEYID' uses specified key
- 'secret unlockers add pgp --keyid=KEYID' also works
- Errors if key is already added or no default key exists