Idempotent: if the docId is already tracked as PENDING the function
increments attempts, updates lastProbedAt, and recomputes
nextProbeAfter — firstObservedAt is never overwritten.
If the docId already has a terminal status (RESOLVED, ESCALATED) it is
left unchanged.
Record a document as CONTENT_PENDING.
Idempotent: if the docId is already tracked as PENDING the function increments
attempts, updateslastProbedAt, and recomputesnextProbeAfter—firstObservedAtis never overwritten. If the docId already has a terminal status (RESOLVED, ESCALATED) it is left unchanged.