kiro-validate-impl's feature-level requirements-coverage pass found two
low-severity gaps: Requirement 4.1 (discard removed-field values without
error) had no citing task, though it was already satisfied structurally
by task 1.1's direct removal + capnp's default decode behavior -- cited
now on task 5.1, where it's live-exercised. Requirement 3.3's citing task
(5.2) didn't document how worker-liveness was verified -- added a
clarifying bullet recording the actual (indirect, code-path-untouched)
verification method.
No functional changes.