Follow-up to #92745 after maintainer autoreview found that the skipped recall event widened the shipped MemoryHostEvent union and changed limited legacy reads.
Keep readMemoryHostEvents() source-compatible by filtering diagnostic records before applying limits, and expose skipped recall diagnostics through the opt-in MemoryHostEventRecord/readMemoryHostEventRecords path.
Original skipped-recall behavior landed in #92745 by @mushuiyu886.
Record diagnostic events when memory_search returns durable memory hits that are intentionally excluded from short-term promotion, so users can distinguish eligibility decisions from recall tracking failures.
