Add docs and further stress tests to the demo

docs/architecture.md

@@ -8,6 +8,8 @@ A forward drag calls `router.resolve()` and Vue Router's public `loadRouteLocati
 
 Each preview subtree receives a scoped `routeLocationKey`, so `useRoute()` returns preview params even though the global route is not committed. A normal `router.push()` or `replace()` runs only after the gesture chooses to commit. A guard failure cancels the transaction and removes the preview.
 
+Preview routes can contain ordinary Vue `<Suspense>` boundaries. A route may therefore become a live navigation surface immediately, show its fallback while async child setup continues, and preserve the resolved child when the route later moves into the mounted cache. Route guards remain commit-time authority and can still reject that cached destination on a later entry attempt.
+
 ## Transaction lifecycle
 
 Transactions move through `interactive`, `committing`, `settling`, and cancellation states. They expose normalized progress and velocity plus `fromKey`, `toKey`, direction, presentation, and optional source geometry.