review-wave-6 — the wave-6 gate passes, engine-mem.md flipped to stable

The born-pinned gate audited the mem engine against the contract and
ADR-024: the conformance read clean in mechanism substance (queue
state machine, scheduler collapse, outbox, streams, locks, clock,
validation, tx overlay, wake substrate — incl. a full guard-order and
panic-hygiene audit); the suite's third column read row-by-row and
25/25 green under the per-test current-thread flavor (24 engine-shared
rows + mem's payload_too_large non-occurrence arm + the factory-shape
test); three-way arithmetic equivalence green on all columns; the
wasm32 acceptance items verified (compile-clean, tokio sync+time,
no blocking, flavor enforced); the rider's two arms verified (Finding
1 discharged; Findings 2-3 stay parked for wave 7); workspace gates,
taskgraph validate green.

Three edge-domain fixes landed inline: the stream cursor read's
i64::MAX overflow (Bound::Excluded), trim_to's i64::MAX horizon
endpoint (Bound::Included), and the scheduler register path now
rejecting a parseable interval whose first boundary overflows with
InvalidSpec — the one engine-vs-engine divergence the read found,
aligned into the class-1 window — plus a pinning test and scaffold-
residue doc/comment cleanups (clock allows, tx per-stream wake
comment, wakes/stream module docs). Recorded findings with
dispositions in the task's Notes for the wave-7 pre-release pass:
the multi-thread publish-to-wake ordering tolerance, the heartbeat/
save_offset/EventReceiver-try_recv ADR-023 §2 classification gaps,
and the mem arithmetic being a suite-pinned transplant.

Verified: cargo build; cargo test --workspace green (mem 101 lib +
25 suite, sqlite 191+25, pg 124+25+9 server-less, core 25, harness 3);
clippy --all-targets -D warnings clean; fmt clean; taskgraph validate
(61 tasks). Gate record: tasks/review-wave-6.md (Notes + Summary),
implementation.md wave-6 row + review-rounds entry.

alkstore-mem/src/wakes.rs

@@ -6,8 +6,9 @@
 //! commit order; coalescing is not applicable. The substrate realizes
 //! the shape structurally:
 //!
-//! - **Commit-ordered source**: a mechanism (notify now — streams and
-//!   queue wakes arrive with their tasks) fires its commit's wakes
+//! - **Commit-ordered source**: a mechanism (notify, stream publishes,
+//!   the tx commit-merge's staged notifies and publishes) fires its
+//!   commit's wakes
 //!   through [`WakeBus::fire_commit_wakes`], under one guard: the
 //!   commit sequence bumps and the per-channel fanout completes as a
 //!   single operation, so every subscriber's receipt order is exactly