nx_commons_store_probe_gate.nx

nx_commons_store_probe_gate.nx -- BISECT the hang in nx_commons_ledger_e2e_gate. That gate printed its header and then timed out at 12s, so it blocked inside the store calls and never reached its first post-write print. Guessing which call blocks would be a patch cascade; this prints a marker before and after EACH store call so the blocking one names itself. license_tier: ORIGINAL expect_exit: 0