fix: use put_nowait to avoid race condition on queue full check

[hussein-awala]

Summary

• The previous code checked queue.full() then called await queue.put() as separate operations
• Between the check and the put, another coroutine could add an item (after yielding at await), causing the put to block unexpectedly or the check to be stale
• Fix: use put_nowait() and catch asyncio.QueueFull to make the check-and-put atomic

Test plan

• test_max_queue_size still passes
• All unit tests pass

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