* Use DynamicLatch in DispatchQueue to avoid main thread spinning
Replace the busy-yielding pending_task_count_ loop in DispatchQueue::finishTasks
with a blocking DynamicLatch. This avoids having the main thread consume CPU
cycles while waiting for dispatched tasks to complete.
The DynamicLatch implementation uses C++20 std::atomic::wait/notify_all for
efficient blocking and wakeup, with proper release-acquire semantics to ensure
task results are visible to the waiting thread.
* Reformat DynamicLatch to match DispatchQueue style
* Update attribution headers in DispatchQueue files to note modifications
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