Close the DESIGN-HANDOFF open question "empty and error states are
unspecified" with a written addendum (design/PANEL-EMPTY-STATES.md)
and its implementation in both panel cards:
- quest log resolves one state in priority order: no adventurer in
the path, integration not set up, records unreachable
(unavailable/unknown), away via direct navigation, all-clear
zero-quest day, all-done fallback before the 1c takeover, then the
normal three-window columns
- party board renders a notice instead of an empty grid when no
children are configured or every child's sensors are unresolvable,
and muted "Unknown" plates for partially unresolvable children
- a shared notice panel (panel tokens, role=status) replaces every
state that would otherwise render a blank parchment; frames,
kicker and dock always stay