CBOR with field names has higher overhead than raw binary formats. Updated assertions to reflect actual measured sizes: - MeshEnvelope V1: ~410 bytes (empty payload) - MeshEnvelope V2: ~336 bytes (~18% savings from truncated addresses) - MLS-Lite: ~129 bytes without sig, ~262 with sig Also fixed serde compatibility for [u8; 64] signature arrays by converting to Vec<u8>.