Refactor SIMD gather, tighten constraints, doc & test opts

- Require TLane : unmanaged, ISPMDLane for stricter type safety and direct memory ops
- Refactor GatherVectorN and WideLane<T>.Gather to use Unsafe.SkipInit and direct assignment, removing stackalloc and TLane.Load for better SIMD performance
- Use Vector.Sum in WideLane<T>.ReduceAdd
- Add/improve XML docs for ReduceAdd/ReduceMax/ReduceMin
- Update test project for AOT, AVX2, speed optimization, and disable reflection
- Tweak GGXMipGenerationBenchmark and Program.cs for improved benchmarking and output

Misaki.HighPerformance.Test/Benchmark/GGXMipGenerationBenchmark.cs

@@ -1,5 +1,4 @@
 using BenchmarkDotNet.Attributes;
-using BenchmarkDotNet.Diagnosers;
 using BenchmarkDotNet.Engines;
 using Misaki.HighPerformance.Image;
 using Misaki.HighPerformance.Jobs;
@@ -396,8 +395,8 @@ public unsafe class GGXMipGenerationBenchmark
     [GlobalSetup]
     public void Setup()
     {
-        //const string imagePath = "F:\\c\\SimpleRayTracer\\native\\assets\\hdri\\golden_gate_hills_1k.hdr";
-        const string imagePath = "C:\\Users\\Misaki\\Downloads\\grasslands_sunset_4k.hdr";
+        const string imagePath = "F:\\c\\SimpleRayTracer\\native\\assets\\hdri\\golden_gate_hills_1k.hdr";
+        //const string imagePath = "C:\\Users\\Misaki\\Downloads\\grasslands_sunset_4k.hdr";
         using var stream = new FileStream(imagePath, FileMode.Open, FileAccess.Read);
         _image = ImageResultFloat.FromStream(stream, ColorComponents.RGB);