feat(core): a cable carries one frame after the other, as in Java

Java's SimplexVerbindung sleeps a cable's delay with the port's buffer
locked: frames on one cable leave one after the other, and a frame shows
in the packet log when it leaves. The engine now queues a frame in the
output buffer until the one before has arrived (ethernetLinkDeparture).
Swift sends a cable's frames at once; the option swiftCables keeps that for
the Swift comparison, which goes on checking everything else trace by
trace.

With the queue, the Java comparisons match within 120 ms (was 200); a
state of the TCP stories within 250 ms, where the engine's calls block
one after the other.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/core/test/oracle.test.ts

@@ -72,7 +72,8 @@ function observationJson(item: IcmpObservation): Record<string, unknown> {
 }
 
 function run(scenario: Scenario): Record<string, unknown> {
-  const engine = new NetworkRuntimeEngine(scenario.seed);
+  // Swift's cables carry all frames at once; everything else is compared as it is.
+  const engine = new NetworkRuntimeEngine(scenario.seed, undefined, { swiftCables: true });
   if (scenario.speedPercent !== undefined) engine.setSimulationSpeed(scenario.speedPercent);
   engine.handle({ type: 'start', snapshot: snapshotOf(scenario), seed: scenario.seed, initialTimeMilliseconds: 0 });