rvoip-core-traits 0.3.5

Pure-data trait + type surface for the rvoip ecosystem. Holds ID newtypes and Identity data types so consumer crates (auth-core, vcon, harness, adapters) can depend on the type surface without pulling in rvoip-core's implementation. Carved out to break the rvoip-core → rvoip-vcon → rvoip-auth-core → rvoip-core dependency cycle (GAP_PLAN V2.A).