be_uuid_dec decodes time_mid with wrong byte order (le16dec instead of be16dec)

Summary

be_uuid_dec(:361) reads time_mid via le16dec(p+4) but be_uuid_enc(:345) writes via be16enc(p+4). Asymmetric endian: encode is big-endian, decode is little-endian. Round-trip produces byte-swapped time_mid on LE host. No in-tree callers (dead code). Latent data corruption for future caller.