nx_wflow_approve_capacity_gate_t278.nx

nx_wflow_approve_gate.nx -- R4 HUMAN-IN-THE-LOOP approvals gate. An `approve` step PARKS the run (status=WAIT, in-flight -- neither DONE nor FAILED) until an operator decision record lands on the SAME event-sourced ledger (WFDEC ... decision=APPROVED|DENIED by=<who>); wf_resume then completes or fail-stops it. DENY WINS (fail-safe). Proves: parked run gates later steps; resume WITHOUT a decision never fabricates approval; APPROVED unlocks exactly once (no re-exec of OK steps); DENIED fail-stops; bad decision word refused; a decision for the WRONG step does NOT unlock. ZERO forks. license_tier: ORIGINAL expect_exit: 0