fix(sound): collapse the OSD track row when the player goes away

A Loader keeps the height of its last item after active goes false. When
a browser tab playing media was closed, its MPRIS player vanished,
Player.active dropped and the window shrank to 100px, but the Loader
still reserved 46px plus the Column spacing on top. The volume row was
pushed down and clipped at the bottom edge, which is the "stuck" OSD a
hot reload used to cure: a fresh Loader starts at zero height.

Hiding the Loader while inactive makes the Column skip it. Both the
retained height and the collapse were confirmed with headless qml6 runs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions