Extracts the self-contained "hidden-view parking" slice from PR #7214
(orca-performance) as a standalone fix for the Windows renderer OOM/hang
under multi-agent load (#7175 / STA-476): long-hidden terminal panes
unmount after a 30s hysteresis while a pane-less byte watcher keeps
bell/title/agent-completion side effects alive; reveal rides the existing
tab-move reattach path.
Byte mode only: no main-process side-effect emitter ships here, so
constants.ts pins terminalMainSideEffectAuthority / terminalHiddenDeliveryGate /
terminalModelQueryAuthority to false (the single intentional divergence from
#7214, reconciled by taking #7214's values when its emitter lands). The
parking kill switch terminalHiddenViewParking also ships default-OFF
(opt-in) until the memory win is confirmed in a soak.
Co-authored-by: Jinwoo-H <jinwoo0825@gmail.com>
Co-authored-by: Orca <help@stably.ai>
