dequeue_event() raises RuntimeError; EventConsumer expects TimeoutError/QueueEmpty

[TadakiAsechi]

Problem: When no events are available, dequeue_event() raises RuntimeError. EventConsumer expects asyncio.TimeoutError (to keep polling) or asyncio.QueueEmpty (when no_wait or queue closed), so behavior can be wrong (e.g. early exit).

Cause: RedisStreamsEventQueue.dequeue_event() wraps "no events" in RuntimeError instead of raising the exception types the SDK uses for control flow.

Fix: Raise asyncio.TimeoutError when no events and no_wait=False; raise asyncio.QueueEmpty when no events and no_wait=True, or when queue is closed. Re-raise these instead of wrapping in RuntimeError.