commit_resolve() delivers a registered continuation's outcome exactly
once (idempotent re-resolve), dispatched off-thread via
vtask_enq_classified(VTASK_LIVE_BLOCK) so it never runs inline on the
replication-ACK or iomgr path. Wired into all 6 commit.c-internal
paths that can advance committed_lsn/writable_lsn.
Review caught a real task-graph gap, not a defect: converting
COMMIT_MODE_WAIT away from a blocking wait also removes the only
mechanism that ever detected a commit timing out (the caller's own
cond_timedwait deadline). Nothing yet arms an equivalent timeout for
async-registered continuations, and nothing wires demotion/log-truncation
detection to commit_resolve(FAILED, ...) -- left as-is, a pending async
command during quorum loss would hang forever instead of failing,
which is worse than today. Split into new tasks 1.3 (timeout arming)
and 1.4 (demotion/truncation wiring), renumbered the old concurrency
test to 1.5, and made 3.2 depend on both since its failure/timeout
observable is meaningless without them. design.md's File Structure
Plan updated to reflect that ha.c/persist.c need a narrow touch for
1.4's detection hooks.