…ul terminator)

….spv/.hlsl side by side

A .sdfx containing 'partial shader Foo' used to silently emit broken
C# (mixin syntax inside a generated class, failing with CS0246 on the
'mixin' parameter name). Detect a ShaderClass declaration in a .sdfx
file and emit a clear #error directing the user to use 'effect' or
'partial effect' instead.

…xt is missing

Apply std430 base alignment to vector members and round ArrayStride up to struct alignment when emitting [RW]StructuredBuffer element types. Relaxed block layout allows scalar-aligned vectors but forbids them straddling 16-byte boundaries, and requires array-of-struct stride to match the struct's base alignment.

Previously RWStructuredBuffer<Test> where Test = { float3 A1; float2 A2 } emitted ArrayStride=20 with A2 at offset 12 — valid D3D packing but rejected by spirv-val.

MatrixType in TypeSizeInBuffer had a stray * 4 in the StructuredBuffer branch, so float4x4 reported 256 bytes instead of 64. Any RWStructuredBuffer<struct-with-matrix> would have emitted a broken ArrayStride — luckily the only real user is InstanceTransform, a float4x4 inside its own struct, and that path wasn't validated by a unit test.

Replace the formula with std430 strict matrix layout: each column (ColumnMajor) or row (RowMajor) is padded to its std430 base alignment. Covers non-square matrices correctly under Vulkan relaxed block layout.

Adds CSMatrix.sdsl regression test covering RWStructuredBuffer<Transform> where Transform = { float4x4 Matrix; float3 Scale }.

Reintroduced when Stride.Build.Sdk was merged from master (PR stride3d#3085);
sdsl-rewrite had already switched to the Roslyn source generator.
The stale wiring caused VS to regenerate .sdsl.cs/.sdfx.cs on disk,
which then collided with the Roslyn-emitted obj/ files (CS0111/CS0579
duplicate types).

…ily reproducible

…me + CPU rounding differences)

TransitionDescriptorResources skipped resources whose NativeResourceState
was GenericRead or CopyDest, treating those states as upload/readback
heap markers. That conflates heap type (a lifetime property of Upload/
Readback heaps) with transient state (a Default-heap resource can be in
CopyDest after a Copy/Resolve/UpdateSubresource). The skip silently
dropped the binding-time transition and left stale layouts leaking into
the next SRV/Present — D3D12 GPU validation 'Incompatible texture
barrier layout', SRV sampling in LEGACY_COPY_DEST, WARP 1.0.18 missing
glyphs in dynamic sprite font tests, back-buffer Present failing in
COPY_SOURCE on RenderToWindow.

Track heap type explicitly: add IsHostVisibleHeap on GraphicsResource,
set at resource creation (Upload/Readback → true, Default → false). Draw
prep skips on that flag, not on state. Default-heap resources in
CopyDest/CopySource/GenericRead after a copy go through the normal
transition to ShaderResource at next bind — single barrier, no reliance
on a post-copy Common transition and on barrier coalescing to merge it.

Stride's D3D12 backend carried two parallel runtime-barrier paths (legacy
ResourceStates and enhanced BarrierLayout) plus dual per-resource state
tracking (NativeResourceState + LayoutTracker). The legacy path brings the
full D3D12 quirk set — implicit state promotion, decay at ExecuteCommandLists,
COMMON == PRESENT == 0x0 ambiguity — which don't exist in the enhanced
model or in Vulkan. Enhanced Barriers are supported everywhere Stride
actually targets (NVIDIA 531.18+, AMD 23.5.2+, Intel Arc 31.0.101.4032+,
WARP, Xbox Series), so the fallback is technical debt.

Also found: the existing SupportsEnhancedBarriers detection was reading
EnhancedBarriersSupported at the wrong struct offset (8 instead of 4)
and the oversized 64-byte buffer made CheckFeatureSupport return
E_INVALIDARG on some devices. Net result was the enhanced flush path had
never actually run in production — legacy was silently in use, which is
where the GPU-validation regressions that prompted this lived. Fixed by
using Silk.NET's FeatureDataD3D12Options12 struct directly.

Changes:
  * GraphicsDevice.Direct3D12: throw GraphicsDeviceException at init if
    Enhanced Barriers unsupported. SupportsEnhancedBarriers field gone.
  * CommandList.Direct3D12: delete FlushResourceBarriersLegacy. Delete
    the legacy/enhanced branch in FlushResourceBarriers — enhanced is
    the only path. Delete obsolete ResourceBarrierTransition(GraphicsResourceState)
    overload. Replace sort+merge coalesce with an order-preserving
    Dictionary<(Resource, Subresource), int> dedup — no reliance on
    List.Sort stability and no GetHashCode collision edge cases.
  * GraphicsResource.Direct3D12: delete NativeResourceState field and
    IsTransitionNeeded(ResourceStates) method — no runtime consumers
    after legacy removal. LayoutTracker is now the single source of
    truth for per-subresource state.
  * Buffer / Texture / BarrierMapping: rename local NativeResourceState
    writes to desiredResourceState. ResourceStates is now creation-only
    (CreateCommittedResource and the init-time copy-queue barriers);
    ToBarrierLayout remains as the creation-to-runtime bridge, annotated
    as such. ToResourceStates had zero callers after the runtime
    cleanup — removed.

Result: one runtime barrier path, Vulkan-shaped (BarrierLayout drives
access/sync derivation at flush time). Smaller surface, fewer places
where field-vs-tracker drift or sort-stability matter.

…ackends

- IsHostVisibleHeap moved from Direct3D12 to GraphicsResource base; Vulkan
  sets it for Staging/Dynamic buffers and Staging textures.
- Texture.GetInitialBarrierLayout consolidates the Usage/flags → BarrierLayout
  ladder; D3D12 and Vulkan init both call it.
- Re-adds BarrierMapping.ToResourceStates (D3D12) to bridge shared
  BarrierLayout back to the ResourceStates CreateCommittedResource needs.