UE5 5.5's FVoiceModule returns NULL encoder/decoder, breaking
Opus-based audio replication. This adds a transparent fallback:
- Server sends raw PCM when OpusEncoder is null (~32KB/s, fine for LAN)
- Client accepts raw PCM when OpusDecoder is null
- Changed MulticastReceiveAgentAudio from Unreliable to Reliable
to handle larger uncompressed payloads without packet loss
- Added OnlineSubsystemNull config for future Opus compatibility
- Removed premature bAgentSpeaking=true from MulticastAgentStartedSpeaking
to fix race condition with audio initialization
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>