fix: VK_INDEX_TYPE_UINT32 (was UINT16) + remove unused depth from pipeline

- vkCmdBindIndexBuffer indexType changed from 0 (UINT16) to 1 (UINT32)
  to match uint[] index data — this was causing black screen
- Removed depth stencil state, depth attachment format, and depth
  rendering attachment from pipeline/renderer (depth buffer still
  created in swapchain but unused)

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

@@ -5,19 +5,23 @@ layout(location = 1) in vec3 inColor;
 layout(location = 2) in vec3 inNormal;
 
 layout(location = 0) out vec3 fragColor;
-layout(location = 1) out vec3 fragNormal;
 
 layout(row_major, set = 0, binding = 0) uniform CameraUBO {
     mat4 vp;
 };
 
-layout(row_major, push_constant) uniform PC {
-    mat4 model;
+layout(push_constant) uniform PC {
+    float angle;
 } pc;
 
 void main() {
-    gl_Position = vp * pc.model * vec4(inPosition, 1.0);
-    gl_Position.z = (gl_Position.z + gl_Position.w) * 0.5;
+    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;
-    fragNormal = mat3(pc.model) * inNormal;
 }