#3640 v3 outbox killed-writer test times out waiting for the kill point under CPU load

integration/datastore_v3_outbox_test.ts, test 'v3 outbox: a writer killed before its append lands is landed once by the next writer, which keeps its file' (line 261), failed in verify-build with: waitFor: timed out after 10000ms waiting for the writer to reach its kill point (killWriter, line 162).

Seen 2026-10-19 in verify-build run b8901d67-70fe-4aea-a666-e1e5a699a0f3 for swamp-club#3611, whose change does not touch datastore_v3 or the outbox. The run shared the host with verify-reviews and verify-skills. The file passes 10/10 in isolation on the same commit. Likely the same load sensitivity as swamp-club#3639: the 10 s waitFor budget for the child writer to reach its kill point is too tight when the host is busy. Expected: the test waits on the writer's own signal without a wall-clock budget that load can exhaust, or with one scaled for full-suite load.