Widens the stranded-done recovery branch so a reaped task-less validating/done
feature is re-driven to a terminal verdict instead of stalling its slice forever
(closes the reaper->slice-deadlock P0). Adds a Surface Enumeration + adversarial
re-drive reliability suite (git-clean, no duplicate Fix Features, terminal
verdict, no deadlock) gating release. Updates missions docs + CONCEPTS for the
default-to-fail posture, non-mutating verification, and inconclusive verdict.
Adds changeset.
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