fix(omo-senpi): name the nudge-only rule when a kibitzer hint is rejected

The nudge tool now admits hints through memory-core's describeInvalidHint. A
hint that addresses the agent comes back with the rule and the fix - "The hint
addresses the agent (second person or imperative): restate what the note records
as a plain observation." - instead of the generic shape complaint, so the one
correction the contract allows can be a real correction. Secret-like material is
checked first and keeps its own reason when a hint breaks both rules, and the
hint parameter description states the observation-only shape the judge is asked
for.