treat ad-hoc epics as perpetual in roadmap/audit (alias-aware) (#2126) (#2160)
Phase 1 (epic #85). roadmap._is_standing becomes _is_perpetual and matches either 'ad-hoc' or the deprecated 'standing' alias, so ad-hoc buckets are excluded from the strategic roadmap (and from epic-drift, which reads the same gather). This preserves the canonical 'epic AND NOT ad-hoc' strategic view. epic_audit/rollup/epic-create docstrings and help updated to ad-hoc wording. No behavior change for standing during the rollout window.