Add PEM import/export support for LMS keys

[PrithviPai24]

Hi Team,

I am new to this space and trying to understand the current capabilities of the tool. I have a requirement to work with LMS public keys in PEM format:

1. Parse an LMS public key in PEM format which comes from webserver.
2. Decode the public key.
3. Pass the decoded data to a device in the expected binary layout.

From reading the code and trying the demo tool, it looks like key material is currently handled only as custom binary (*.prv, *.aux, *.pub), and there is no support for importing or exporting LMS keys in PEM (e.g. -----BEGIN PUBLIC KEY----- with an LMS OID/SubjectPublicKeyInfo wrapper).

My use case is to keep the device‑facing format exactly as you define it today, but to have a more interoperable format (PEM) for storage, transport, and inspection in other parts of the toolchain (which are already PEM/X.509‑centric).

Any guidance or pointers to existing work, even experimental branches, would be greatly appreciated.

Thanks,
Prithvi Pai