feat: push constants + UBO descriptor sets — rotating triangle with VP matrix

- Push constants: rotation angle (float) sent to vertex shader via vkCmdPushConstants
- UBO + descriptor sets: VP matrix (mat4) in uniform buffer, bound via VkDescriptorSet
- New Vulkan functions: vkCreateDescriptorSetLayout, vkCreateDescriptorPool,
  vkAllocateDescriptorSets, vkUpdateDescriptorSets, vkCmdBindDescriptorSets,
  vkCmdPushConstants
- New structs: VkPushConstantRange, VkDescriptorSetLayoutBinding,
  VkDescriptorSetLayoutCreateInfo, VkDescriptorPoolCreateInfo,
  VkDescriptorPoolSize, VkDescriptorSetAllocateInfo, VkWriteDescriptorSet,
  VkDescriptorBufferInfo
- Per-frame UBO buffers (HOST_VISIBLE|HOST_COHERENT, 64 bytes each)
- Perspective projection + look-at camera (static, no ECS yet)
- Cleaned up debug logging in VulkanContext
- Zero validation errors

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

@@ -6,7 +6,22 @@ layout(location = 2) in vec3 inNormal;
 
 layout(location = 0) out vec3 fragColor;
 
+layout(row_major, set = 0, binding = 0) uniform CameraUBO {
+    mat4 vp;
+};
+
+layout(push_constant) uniform PC {
+    float angle;
+} pc;
+
 void main() {
-    gl_Position = vec4(inPosition, 1.0);
+    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);
     fragColor = inColor;
 }