- Added `kms export` and `kms import` commands to manage file-backed signing keys.
- Implemented `HandleKmsExportAsync` and `HandleKmsImportAsync` methods in CommandHandlers for exporting and importing key material.
- Introduced KmsPassphrasePrompt for secure passphrase input.
- Updated CLI architecture documentation to include new KMS commands.
- Enhanced unit tests for KMS export and import functionalities.
- Updated project references to include StellaOps.Cryptography.Kms library.
- Marked KMS interface implementation and CLI support tasks as DONE in the task board.