Job system priorities, async waits, parallel map/queue

Major refactor:
- Add job priority tiers and async wait APIs to IJobScheduler
- Implement priority-based job queues and scheduling logic
- Introduce UnsafeParallelHashMap and refactor UnsafeParallelQueue
- Refactor UnsafeSlotMap to chunked storage for scalability
- Update SlotMap/ConcurrentSlotMap for consistency and perf
- Add new benchmarks and unit tests for parallel collections
- Misc: add MemoryUtility.AlignUp, version bumps, test improvements, bug fixes

Misaki.HighPerformance.LowLevel/Collections/HashMapHelper.cs

@@ -166,7 +166,7 @@ public unsafe struct HashMapHelper<TKey> : IDisposable
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static int CeilPow2(int x)
+    internal static int CeilPow2(int x)
     {
         x -= 1;
         x |= x >> 1;