Start-guard covers a static detour chain but stops at a selector (its
chosen member is runtime-resolved). This adds the runtime half: in
Selector.SelectOutbound, BEFORE committing the switch, if the new member
reaches a wireguard endpoint, walk up the reverse-dependency ledger
(OutboundManager.ConsumersOf) and SuspendAmneziaWG() every AmneziaWG
consumer of the group — device down, started=false. Suspending before
s.selected.Store closes the race: by the time the group points at the WG
member, the consumer is down and a reconnect fails with "not ready"
instead of sending a junk handshake into WireGuard.
New adapter.AmneziaWGSuspendable marker + OutboundManager.ConsumersOf let
protocol/group act without importing protocol/wireguard. Plain-WG and
non-AWG consumers are left untouched. Variant B throughout.
Refs #2
