fix: consolidate KeyMeta interface and improve type safety

- Remove duplicate KeyMeta interface from crypto/vc/index.ts
- Import KeyMeta from common.ts as single source of truth
- Add missing fields to KeyMeta interface (identity, passkeyCredIdHex)
- Remove unused ErrorResponse interface from endorserServer.ts
- Fix import path for KeyMeta in crypto/vc/index.ts

This change resolves type compatibility issues and ensures consistent
KeyMeta type usage across the codebase.

src/interfaces/common.ts

@@ -43,6 +43,8 @@ export interface KeyMeta {
   derivationPath: string;
   registered?: boolean;
   profileImageUrl?: string;
+  identity?: string;  // Stringified IIdentifier object from Veramo
+  passkeyCredIdHex?: string;  // The Webauthn credential ID in hex, if this is from a passkey
   [key: string]: unknown;
 }