feat(vulkan): run the compute/UI path without VK_EXT_descriptor_heap

Device::Initialize required twelve device extensions with no capability
check. Mesa Turnip (Adreno) lacks six of them: VK_EXT_descriptor_heap,
VK_KHR_shader_untyped_pointers, VK_EXT_device_fault and the three ray
tracing extensions. vkCreateDevice failed there, so not even a UI-only
program could start, although the UI path is compute-only and needs
nothing else that Turnip is missing.

The descriptor heap, ray tracing and device fault are now optional
groups, detected at start-up from the extension list and the feature
bits (Device::descriptorHeapSupported, rayTracingSupported,
deviceFaultSupported). Ray tracing needs the heap; on a device without
it the ray tracing entry points throw a message naming the cause.

Without the heap the same bindless slots live in one update-after-bind
descriptor set per frame, owned by DescriptorHeapVulkan: binding 0
storage images, 1 sampled images, 2 samplers, 3 storage buffers. Slot
allocation, the slot handles, UIDispatchHeader and the UIRenderer API
are unchanged; buffer slots simply stop being offset. Window::Render
binds that frame's set where it binds the heap, every compute pipeline
shares the heap object's pipeline layout, and push data travels as push
constants.

Each UI kernel is built twice from one source. ui-shared.glsl declares
its resources through UI_HEAP_* macros that expand to descriptor_heap
or, with CRAFTER_GRAPHICS_DESCRIPTOR_SETS defined, to set/binding.
<name>.comp.spv and <name>.comp.sets.spv ship side by side and
ComputeShader::Load picks one. The heap build of every shader is
byte-identical to before.

Breaking:
- ComputeShader::Load takes the heap as a second argument.
- DescriptorHeapVulkan is no longer copyable or movable.
- Custom UI shaders declare heap resources with the UI_HEAP_* macros
  and are registered twice in project.cpp (see the README).
- project.cpp uses Shader::defines and Shader::variant, so it needs a
  crafter-build that has them (Crafter.Build master, fe38cc1 or later).

Also:
- maintenance5 is enabled as a feature, not only as an extension:
  every VulkanBuffer already relied on VkBufferUsageFlags2CreateInfo.
- Barrier stage masks drop RAY_TRACING_SHADER on devices without ray
  tracing, and ImageVulkan::Create resolves its default consumer stage
  to COMPUTE_SHADER there.
- Window refuses a swapchain whose image count is not numFrames
  instead of writing past images[]. The limitation itself is #160.
- CRAFTER_GRAPHICS_NO_DESCRIPTOR_HEAP forces the fallback on a driver
  that has the heap, so it can be exercised on a desktop GPU.

Verified on an RTX 4090 in both modes under the validation layer, and
on a Fairphone 6 (Turnip, Adreno 810, postmarketOS), where the fallback
is the only path.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

shaders/ui-shared.glsl

@@ -8,7 +8,31 @@
 
 #extension GL_EXT_shader_image_load_formatted : enable
 #extension GL_EXT_shader_explicit_arithmetic_types_int16 : enable
+
+// ─── binding model ──────────────────────────────────────────────────────
+// Every shader that includes this file is compiled twice from one source.
+// The default build indexes VK_EXT_descriptor_heap directly. The second
+// build defines CRAFTER_GRAPHICS_DESCRIPTOR_SETS and reads the same slots
+// from one bindless descriptor set, for drivers without the heap extension
+// (output: <name>.sets.spv, picked by ComputeShader::Load at runtime).
+//
+// Declare bindless resources with these macros instead of writing
+// `descriptor_heap` or a set/binding pair, and both builds stay in sync.
+// Slot numbers mean the same thing in both: UI_HEAP_IMAGES and
+// UI_HEAP_TEXTURES share one image slot space, and any number of buffer
+// blocks may alias UI_HEAP_BUFFERS.
+#ifdef CRAFTER_GRAPHICS_DESCRIPTOR_SETS
+#define UI_HEAP_IMAGES   set = 0, binding = 0
+#define UI_HEAP_TEXTURES set = 0, binding = 1
+#define UI_HEAP_SAMPLERS set = 0, binding = 2
+#define UI_HEAP_BUFFERS  set = 0, binding = 3
+#else
 #extension GL_EXT_descriptor_heap : enable
+#define UI_HEAP_IMAGES   descriptor_heap
+#define UI_HEAP_TEXTURES descriptor_heap
+#define UI_HEAP_SAMPLERS descriptor_heap
+#define UI_HEAP_BUFFERS  descriptor_heap
+#endif
 #extension GL_EXT_nonuniform_qualifier : enable
 #extension GL_EXT_buffer_reference : enable
 
@@ -16,9 +40,9 @@
 // The same heap slot can be read as either uiImages[] (storage image) or
 // uiTextures[] (sampled image) depending on which descriptor was written
 // at that slot. Samplers live in a separate sampler heap.
-layout(descriptor_heap) uniform image2D    uiImages[];
-layout(descriptor_heap) uniform texture2D  uiTextures[];
-layout(descriptor_heap) uniform sampler    uiSamplers[];
+layout(UI_HEAP_IMAGES)   uniform image2D    uiImages[];
+layout(UI_HEAP_TEXTURES) uniform texture2D  uiTextures[];
+layout(UI_HEAP_SAMPLERS) uniform sampler    uiSamplers[];
 
 // ─── push-constant header ───────────────────────────────────────────────
 // Every UI dispatch's push-constant struct begins with this. User shaders
@@ -70,10 +94,10 @@ struct GlyphItem   { vec4 rect; vec4 uv; vec4 color; };
 // ─── SSBO heap views ────────────────────────────────────────────────────
 // One declaration per item type; each shader uses the one matching its
 // dispatch. Indexed by hdr.itemBuffer.
-layout(descriptor_heap, std430) readonly buffer UIQuadBuf   { QuadItem   items[]; }   uiQuadHeap[];
-layout(descriptor_heap, std430) readonly buffer UICircleBuf { CircleItem items[]; }   uiCircleHeap[];
-layout(descriptor_heap, std430) readonly buffer UIImageBuf  { ImageItem  items[]; }   uiImageHeap[];
-layout(descriptor_heap, std430) readonly buffer UIGlyphBuf  { GlyphItem  items[]; }   uiGlyphHeap[];
+layout(UI_HEAP_BUFFERS, std430) readonly buffer UIQuadBuf   { QuadItem   items[]; }   uiQuadHeap[];
+layout(UI_HEAP_BUFFERS, std430) readonly buffer UICircleBuf { CircleItem items[]; }   uiCircleHeap[];
+layout(UI_HEAP_BUFFERS, std430) readonly buffer UIImageBuf  { ImageItem  items[]; }   uiImageHeap[];
+layout(UI_HEAP_BUFFERS, std430) readonly buffer UIGlyphBuf  { GlyphItem  items[]; }   uiGlyphHeap[];
 
 
 // ──── Driver workaround: per-member SSBO load ────────────────────────────