Port the rest of Tauri's volume logic to the Slint bar.
PlayerBar gains a derived vol-locked reproducing Tauri's handleVolumeChange
formula exactly: (alsaDirectHw && !isRemote) || volumeLocked. The local
ALSA-Direct (bit-perfect) lock is lifted while controlling a peer (the
!is-remote term) so the user can adjust the remote renderer; the sink-pushed
NowPlayingState.volume-locked keeps meaning only the peer-disallow half. All
five volume-interaction gates and the slider opacity now read vol-locked.
Force the local player to unity gain (set_volume(1.0)) in bit-perfect, mirroring
Tauri's playerSetVolume(100): when the backend is ALSA + the hw plugin AND a
peer is not the active renderer, set core volume to 1.0 and push
NowPlayingState.volume = 1.0. Applied (a) at the startup audio-settings load and
(b) on backend / alsa-plugin change. Gated on a new is_peer_active() so the
force-100 is skipped while controlling a peer. core().set_volume is the safe
seam; the protected device-init is untouched.
cc
vicrodh
9bb5e6db26