Selecting all routes wipes every explicit selection, so exit nodes fall
back to management's auto-apply flags, which may mark several at once.
Reconcile immediately after select-all so at most one stays active
instead of waiting for the next network map.
A partial selection failure (e.g. an unknown ID in the request) still
selects the valid routes, so run the sibling exit-node deselection
regardless of the error and report both failures together.
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