The two things that decide whether WP9 does anything at all on a device, both
failing silently rather than loudly if missed.
**Capability bits.** The host emits 0xD1 only toward pads that declared they can
render it (arrival flags 8/9). Without `set_pad_audio_caps` the renderer would
sit on a permanently empty plane and look like a decode bug. Declared when the
stream opens, withdrawn when it stops.
**Rumble arbitration.** `valid_flag0` bit 1 (HAPTICS_SELECT) *disables* audio
haptics and selects classic rumble, and `DsDevice` sets it on every rumble write
— as Linux's hid-playstation and SDL both do. One replayed rumble command would
mute the voice coils the 0xD1 stream is driving, for the rest of the session.
Tier A and tier C are mutually exclusive in the pad's firmware, so the
arbitration selects and never blends.
Suppression sits at `nativeNextRumble`, the pull point, rather than in Kotlin:
it keeps the rule next to the reason and covers every caller. The registry is an
atomic bitmask because the reader is the rumble poll thread and must not block
behind a start/stop on the JNI thread.
Order matters on teardown: the capability is withdrawn before the pad returns to
wire rumble, so the host has stopped sending 0xD1 before tier C resumes and the
two never overlap.
`nativeStartPadAudio`/`nativeStopPadAudio` now take the wire pad index, since
both the capability and the arbitration are per-pad. Out-of-range indices are
rejected rather than wrapped into another pad's slot.
12 host tests (2 new, including one pinning that an out-of-range index cannot
shift the mask into undefined territory), 0 clippy findings, check clean on all
three Android ABIs.
enricobuehler
a10bde39bb