Implements the full priority-resolution algorithm: request bus name
with DO_NOT_QUEUE; on EXISTS look up holder Priority via the
Properties interface; if our priority (5) is higher, call
RequestRelease and retry with REPLACE_EXISTING; if equal-or-lower,
return HigherPriorityHolder. AlreadyOwner is treated as success for
same-connection idempotency. Drop releases the bus name and logs
the ReleaseName reply variant.
D-Bus failure paths degrade to a no-op guard so playback continues
exactly as before in environments without a session bus.
Smoke-tested against PipeWire/WirePlumber via dbus-monitor.
cc
vicrodh
bc5d316e5a