compress / decompress helpers for Light Protocol tokens

Added CompressedTokenHelper.compress(...) and .decompress(...) to the z_trade SDK. Light Protocol’s ZK Compression charges roughly $0.000004 per compressed account vs$0.002 for a regular SPL token account — a 500× cost reduction once you’re moving more than a few hundred accounts.

The helper does the boring CPI plumbing: wrap-and-decompose the user’s instruction, route through the Light System Program, attach the 128-byte Groth16 validity proof from a Photon RPC. Saved every consumer ~80 lines of boilerplate.