Build #20 failed to compile on Android because I over-gated the
wzp_proto imports to non-Android. resolve_quality() is compiled on
every platform (it's outside the CallEngine impl) and references
QualityProfile + CodecId — both platform-independent types from
wzp_proto. Move those back to an unconditional import. tracing stays
gated (only the desktop start() body logs; the Android stub is silent).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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