Generate a new keypair for the given encapsulation scheme using a specific RNG.
Note: Only X25519 supports deterministic keypair generation. MLKEM schemes do not support deterministic generation (matching Rust behavior).
The random number generator to use
The encapsulation scheme to use (defaults to X25519)
A tuple of [privateKey, publicKey]
Error if the scheme doesn't support deterministic generation
Generate a new keypair for the given encapsulation scheme using a specific RNG.
Note: Only X25519 supports deterministic keypair generation. MLKEM schemes do not support deterministic generation (matching Rust behavior).