assertNoSeqGaps

Asserts that both dev.ynagai.autograph.Envelope.seq (gapless, +1 within each contiguous run of events sharing a session id — a session rotation restarts it at 1, which is expected and not a gap) and dev.ynagai.autograph.Envelope.globalSeq (gapless, +1 across the whole device lifetime, independent of session) hold wherever each is non-null. Depending on AutographConfig.sequence, only one, both, or neither may be stamped (SequenceMode.None stamps neither, so nothing is checked); events with no envelope are skipped.