feat(8.0): temporal range verbs — diff, history, since(gen|Date), asOf{exclusive}, transactionLog window

asOf() answers "state AT a point"; these answer "what happened BETWEEN two
points" and "one entity's whole history", all on the existing generation records.

- Extract resolveAsOfGeneration() as the shared gen|Date→{generation,timestamp}
  chokepoint (reachability + Date semantics identical everywhere). asOf()'s
  inclusive path is byte-identical — db-mvcc still 25/25.
- asOf(target, { exclusive }) — strict-before (resolved−1, clamped at gen 0,
  never a RangeError).
- db.since(Db | generation | Date) — overload; number/Date resolve via the shared
  resolver (new DbHost.resolveGeneration); EXCLUSIVE lower bound;
  since(db) === since(db.generation). Same-store guard via Db.belongsToStore.
- brain.diff(a, b) → { added, removed, modified } split by nouns/verbs. EARNS its
  name: candidate set is ONLY changedBetween(gLow,gHigh), each classified by
  existence at both endpoints + a key-order-insensitive value compare
  (new src/db/stableEqual.ts) — a touched-but-reverted / born-and-died id is in
  no bucket.
- brain.history(id, { from, to }) → every distinct version oldest→newest, each
  value === asOf(version.generation).get(id); null = removal; kind auto-detected
  (throws on UUID-space collision). New store helper generationsTouching().
- brain.transactionLog({ from, to, limit }) — INCLUSIVE generation/Date window
  (contrast since's exclusive lower bound); limit applied last.
- Compaction policy locked: diff/since THROW GenerationCompactedError below the
  horizon; history TRUNCATES to it.

Types DiffResult/HistoryVersion/EntityHistory exported from the package root.
Tests: tests/integration/db-temporal.test.ts (8 proofs incl. diff-earns-its-name,
history↔asOf cross-check, the composition proof, granularity, compaction contrast)
+ tests/unit/db/stableEqual.test.ts (6). docs/guides/snapshots-and-time-travel.md
+ RELEASES updated. 1477 unit + db-temporal 8 + db-mvcc 25 green.

docs/guides/snapshots-and-time-travel.md

@@ -5,7 +5,7 @@ public: true
 category: guides
 template: guide
 order: 9
-description: Recipes for the Db API — instant backups with persist(), restore, time-travel debugging with asOf(), persist-before-migrate, what-if analysis with with(), and audit trails via transaction metadata.
+description: Recipes for the Db API — instant backups with persist(), restore, time-travel debugging with asOf(), range queries over history (diff, history, since, log windows), persist-before-migrate, what-if analysis with with(), and audit trails via transaction metadata.
 next:
   - concepts/consistency-model
   - guides/optimistic-concurrency
@@ -146,6 +146,96 @@ Three things to remember:
 - Generations reclaimed by `compactHistory()` throw
   `GenerationCompactedError` — persist anything you need to keep forever.
 
+## Range queries over history
+
+`asOf()` answers "what was the state AT a point". Four range verbs answer
+"what happened BETWEEN two points" and "what is one entity's whole history".
+They all build on the same generation records — no extra bookkeeping.
+
+### `diff(a, b)` — what changed, classified
+
+`since()` gives you the raw set of *touched* ids. `diff()` goes further: it
+resolves each touched id at both endpoints and classifies it as **added**,
+**removed**, or **modified** — split by entities (`nouns`) and relationships
+(`verbs`). An id that was touched but ended up identical (changed then
+reverted, or created and deleted within the interval) lands in **none** of the
+buckets. Endpoints are a generation, a `Date`, or a `Db`, in either order:
+
+```typescript
+const d = await brain.diff(1041, brain.generation())
+
+d.added.nouns      // entity ids created between the two states
+d.removed.nouns    // entity ids deleted
+d.modified.nouns   // entity ids whose stored value actually changed
+d.added.verbs      // …relationships, the same three ways
+```
+
+Orientation is `a → b`: `added` means "exists at `b`, not at `a`". The
+comparison behind `modified` is key-order-insensitive, so a no-op re-write of
+the same fields never shows up as a change.
+
+### `history(id, range?)` — one entity, every version
+
+`asOf()` is per-*generation*; `history()` is per-*entity*. It returns every
+distinct version of one id over a range, oldest first — each `value` is the
+materialized state at that version (and `null` marks a removal):
+
+```typescript
+const h = await brain.history(invoiceId)
+
+for (const v of h.versions) {
+  console.log(v.generation, v.value?.metadata?.status ?? '(deleted)')
+}
+// 1041 'draft'
+// 1043 'approved'
+// 1050 'paid'
+```
+
+Every version ties to the trusted `asOf()` path — `v.value` equals
+`(await brain.asOf(v.generation)).get(id)`. Pass `{ from, to }` (generation or
+`Date`) to bound the range; a `from` below the compaction horizon is quietly
+truncated to it rather than throwing (history is best-effort over surviving
+records).
+
+### `since()` and `transactionLog()` take ranges too
+
+`since()` accepts a `Db`, a generation number, or a `Date` — all equivalent,
+all an **exclusive** lower bound (`db.since(prior)` equals
+`db.since(prior.generation)`):
+
+```typescript
+await brain.now().since(1041)                          // ids changed after generation 1041
+await brain.now().since(new Date(Date.now() - 3_600_000)) // …in the last hour
+```
+
+`transactionLog({ from, to })` windows the commit log **inclusively** on both
+ends (a log window names the commits it spans — the deliberate contrast to
+`since`'s exclusive lower bound); `limit` applies after the window, newest
+first:
+
+```typescript
+const window = await brain.transactionLog({ from: 1041, to: 1050 })  // commits 1041…1050
+const recent = await brain.transactionLog({ from: lastHour, limit: 20 })
+```
+
+### Composing them
+
+"Which orders changed in this window?" is `diff` ids intersected with an
+`asOf` query — the two agree by construction:
+
+```typescript
+const changed = await brain.diff(g1, g2)
+const atG2 = await brain.asOf(g2)
+const changedOrders = (await atG2.find({ type: NounType.Document, subtype: 'order' }))
+  .map(r => r.id)
+  .filter(id => changed.added.nouns.includes(id) || changed.modified.nouns.includes(id))
+await atG2.release()
+```
+
+One contrast to keep straight: `diff` and `since` **throw**
+`GenerationCompactedError` for a bound below the horizon, while `history`
+**truncates** to the horizon — diffs must be exact, history is best-effort.
+
 ## Safe schema migration
 
 `brain.migrate()` integrates with snapshots directly: pass `backupTo` and a