[dajiaohuang]

Summary

• Validate all requested parent jobs before inserting a new job into the cache.
• Prevent a rejected job with a nonexistent parent from remaining visible/persisted as an orphan.
• Extend the existing parent-missing test to assert the job is absent after the error.

Validation

• go test -mod=readonly ./job -run '^TestDependentJobsParentDoesNotExist$' -count=1 passed.
• The full suite was not run: the repository CI starts Consul, MongoDB, and MySQL services, which are outside this task's synthetic/local-only test boundary. No service containers were started.
• No CI or review status was queried.