feat: depth buffer + 3D model matrix — rotating cube now looks correct

- Depth image (D32_SFLOAT) + image view created in VulkanSwapchain
- VkPipelineDepthStencilStateCreateInfo: depth test + write enabled, CompareOp=Less
- Push constant changed from float angle (4B) to mat4 model (64B)
- 3D rotation: RotateY * RotateX in renderer, applied via push constant
- Vertex shader: gl_Position = vp * model * vec4(pos, 1.0)
- Depth attachment in VkRenderingInfo + depth clear (1.0)
- Depth image layout transition (Undefined → DepthStencilAttachmentOptimal)
- New Vulkan functions: vkCreateImage, vkDestroyImage, vkGetImageMemoryRequirements, vkBindImageMemory
- New structs: VkPipelineDepthStencilStateCreateInfo, VkStencilOpState, VkImageCreateInfo
- New enums: VkCompareOp, VkImageType, VkImageTiling
- 0 validation errors

src/Engine.Graphics.Vulkan/Shaders/triangle.vert

@@ -10,18 +10,11 @@ layout(row_major, set = 0, binding = 0) uniform CameraUBO {
     mat4 vp;
 };
 
-layout(push_constant) uniform PC {
-    float angle;
+layout(row_major, push_constant) uniform PC {
+    mat4 model;
 } pc;
 
 void main() {
-    float c = cos(pc.angle);
-    float s = sin(pc.angle);
-    vec3 rotated = vec3(
-        inPosition.x * c - inPosition.y * s,
-        inPosition.x * s + inPosition.y * c,
-        inPosition.z
-    );
-    gl_Position = vp * vec4(rotated, 1.0);
+    gl_Position = vp * pc.model * vec4(inPosition, 1.0);
     fragColor = inColor;
 }