0.1.16 | BingBong live voice: return audio

Adds the uplink direction: each player sends their own microphone back to
whoever is puppeting BingBong, gated on proximity to him and attenuated by the
same curve his own voice is heard through. Rides the WebSocket that is already
open, so no new connection, auth or TLS surface, and still nothing over Photon.

Capture postfixes MicWrapper.Read rather than MicrophoneRelay, which copies
only the first 256 samples of each frame. Audio is downmixed, low-passed and
resampled to 16kHz in the mod, then passed through an adaptive noise gate: a
fixed threshold is unusable here because a quiet voice measures below a noisy
room, so the gate learns the background level instead.

F8 mutes the outgoing microphone for the session. uplink_denied and
uplink_roster from the relay are now handled, and the stub relay gained the
return direction plus --deny-uplink to exercise the refusal path.

The real relay and web app do not implement this direction yet, so it currently
only works against the stub.

.gitignore

@@ -226,3 +226,6 @@ artifacts/**/*.zip
 *.txt
 artifacts/**
 Config.Build.user.props
+
+# Per-stream captures written by tools/stub_relay.py's uplink mode
+uplink_*.wav