allMemVectorMetas (memory.go) replaces the identical query-then-scan
block ReembedAll and RepairFactVectors each had for reading id+meta
out of memory_vectors — same query, same json.Unmarshal, different
structs built from the result.
Two RowsAffected() errors were silently dropped with `_`, inconsistent
with every other call site in the same files: AcceptProposedRoutine
now wraps the error instead of treating it as zero rows, and MarkAcked
had it stranded behind a dead branch (both arms returned nil) removed
along with the swallowed error.
No behavior change; internal/store and internal/memory pass with
-race.