Adds 2 targeted tests after confirming tasks 3.1/3.2/3.3 already
cover most of this task's observable criteria:
- N-way expansion swept across sizes {2,3,100,1000} with exact-
endpoint non-leakage checks (existing coverage only tested size 5)
- Requirement 5.2 (individually addressable exactly as a per-element
job) exercised through the real production command dispatch
(job_ctrl(), not the raw key_find() every existing test used) --
confirms an array-expanded element can be cancelled by identity,
siblings stay untouched, and an out-of-range jobid is rejected
Idempotent no-op, forced-failure-then-retry, and partial-reapply
were already fully covered by 3.1/3.2 -- no new tests needed.
Requirement 9.4's node-fencing behavior is confirmed out of this
task's boundary (Live Apply Resource Fence, task 4.x); restore_job_
array()'s own atomicity contract that the fence depends on is
already proven. No production code changed -- test-only.
Task 3.4 of job-array-single-wal-record.