HA assigns panel/hass/narrow/route before the top-level-await entry has
defined the element, so the values landed as own properties that shadowed
the accessors and the card never received hass. And <ha-panel-custom> has
no height, so the percentage host height collapsed the stage to 0 px.
Adopt pre-upgrade properties through the accessors and size the panel from
the viewport minus HA's safe-area padding. The smoke now reproduces HA's
real mount order and container; two mutants guard both contracts. The
bundle is rebuilt from these sources.
Issue: #488
User-Visible: yes
