Two fixes for BT audio silence:
1. Switch Oboe streams from Exclusive to Shared sharing mode. Exclusive
mode bypasses Oboe's internal resampler, so opening a 48kHz stream
against a BT SCO device (8/16kHz only) fails at the AudioPolicy
level. Shared mode lets Oboe's resampler bridge the gap.
2. Add 500ms post-SCO delay before Oboe restart. The audio policy needs
time to apply the bt-sco route after setCommunicationDevice returns.
Without the delay, Oboe opens against the old device (handset).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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