Remove more dead code

- Remove unused loggedCryptoErrors property from BluetoothMeshService
- Remove unused error cases from NoiseEncryptionError:
  - invalidMessage (never thrown)
  - handshakeFailed(Error) (never thrown)

These were identified during deeper code analysis and are
confirmed to be unused throughout the codebase.

bitchat/Services/NoiseEncryptionService.swift

@@ -466,6 +466,4 @@ struct NoiseMessage: Codable {
 enum NoiseEncryptionError: Error {
     case handshakeRequired
     case sessionNotEstablished
-    case invalidMessage
-    case handshakeFailed(Error)
 }