feat: support later function in DeferedQueue

[albertcht]

Summary

Adds a later() method to DeferredQueue, allowing jobs to be scheduled for execution after a specified delay. This brings DeferredQueue to feature parity with DeferQueue and CoroutineQueue.

Changes

src/queue/src/DeferredQueue.php

• Added an explicit constructor accepting ?bool $dispatchAfterCommit and ?Timer $timer (auto-instantiates Hypervel\Coordinator\Timer when none is injected)
• Added later(DateInterval|DateTimeInterface|int $delay, ...) which delegates to Timer::after(), converting the delay to seconds via the inherited secondsUntil() helper, then calls deferJob() so the job still runs inside a deferred coroutine

tests/Queue/QueueDeferredQueueTest.php

• testLaterSchedulesJobWithDelay — integer delay (5 s)
• testLaterWithDateInterval — DateInterval delay (PT10S)
• testLaterWithDateTime — DateTimeInterface delay via a Carbon instance (15 s ahead of frozen now)

All three tests mock Timer and assert that the correct SyncJob and payload reach the handler.

This PR has been merged in v0.3: #361