Define service interfaces in packages/services #352
Description
The credential issuance workflow involves three discrete operations: issuing (signing) a credential, storing the credential, and publishing the credential link. Each of these should be abstracted behind a well-defined interface so that implementations can be swapped without changing consuming code.
These interfaces act as contracts that define the expected behaviour without coupling to a specific implementation. Both the interfaces and their implementations should reside within the packages/services package.
Acceptance Criteria:
- Define IVerifiableCredentialService interface with a method to issue/sign a credential payload and return a signed verifiable credential.
- Define IStorageService interface with a method to store a credential and return the storage URI and hash.
- Define IIdentityResolverService interface with a method to register a credential link against an identifier/scheme.
- All interfaces should have clearly typed inputs and outputs.
- Export interfaces and associated types from the services package.