Refactor SPMD job system, add GGX mipmap benchmark

- Replace IJobSPMD with T4-generated, multi-type SPMD job interfaces and wrappers (up to 8 numeric types)
- Extend ISPMD with Cast/BitCast; implement for ScalarLane and WideLane (SIMD-aware)
- Add unary minus, scalar-lane, and lane-scalar operators to Vector2/3/4; improve Select methods
- WideLane now partial with T4-generated Cast/BitCast (SIMD conversions)
- SPMD job Execute now requires unmanaged TLane; update all usages and benchmarks
- Add GGXMipGenerationBenchmark with vectorized and scalar paths, SkiaSharp output
- Update project files: add generated code, SkiaSharp, bump version to 1.3.0
- Misc: fix formatting, method signatures, FreeList logic

Misaki.HighPerformance.Mathematics.SPMD/Templates/MathV.Vector.tt

@@ -297,8 +297,9 @@ public static unsafe partial class MathV
     {
         return new <#= vectorType #>
         {
-            x = <#= TLane #>.Select(condition, b.x, a.x),
-            y = <#= TLane #>.Select(condition, b.y, a.y),
+<# for (int i = 0; i < dimension; i++) { #>
+            <#= components[i] #> = <#= TLane #>.Select(condition, b.<#= components[i] #>, a.<#= components[i] #>),
+<# } #>
         };
     }
 
@@ -309,8 +310,9 @@ public static unsafe partial class MathV
     {
         return new <#= vectorType #>
         {
-            x = <#= TLane #>.Select(condition.x, b.x, a.x),
-            y = <#= TLane #>.Select(condition.y, b.y, a.y),
+<# for (int i = 0; i < dimension; i++) { #>
+            <#= components[i] #> = <#= TLane #>.Select(condition.<#= components[i] #>, b.<#= components[i] #>, a.<#= components[i] #>),
+<# } #>
         };
     }