Refactor job scheduler API, allocation, and benchmarks

- Removed IJobScheduler interface; merged logic into JobScheduler
- Changed scheduling APIs to accept multiple dependencies (ReadOnlySpan)
- Moved WaitItem classes to JobScheduler.cs and updated types
- Updated JobExecutionContext to use JobScheduler and added docs
- Renamed AllocationManagerInitOpts to AllocationManagerDesc (required props)
- Added thread-safe TotalAllocatedMemory property to AllocationManager
- Refactored Integer to Data in benchmarks; updated usage
- Updated tests and improved documentation throughout

Misaki.HighPerformance.Jobs/JobExecutionContext.cs

@@ -2,21 +2,33 @@ namespace Misaki.HighPerformance.Jobs;
 
 public readonly ref struct JobExecutionContext
 {
+    /// <summary>
+    /// Gets the index of the current thread executing the job.
+    /// </summary>
     public int ThreadIndex
     {
         get; init;
     }
 
-    public IJobScheduler JobScheduler
+    /// <summary>
+    /// Gets the job scheduler that is responsible for managing the execution of jobs.
+    /// </summary>
+    public JobScheduler JobScheduler
     {
         get; init;
     }
 
+    /// <summary>
+    /// Gets the state object for the job scheduler.
+    /// </summary>
     public object? State
     {
         get; init;
     }
 
+    /// <summary>
+    /// Gets the handle for the currently executing job.
+    /// </summary>
     public JobHandle SelfHandle
     {
         get; init;