Shell→dag P6 Part 2 ONLY (predecessor item closed after Part 1 #6619; this half is undone): nbd_proxy_serve_program's RawLine body (&/trap/$! backgrounding, 8 RawLines in dag/extdeps/bmc/webui/nbd_proxy_serve.dag) dissolves into a typed long-running-process/session-lease effect on host_effect_apply - #6629