fix(headless): add missing Effect include and gpu_get_surface stub

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/src/gpu/headless_gpu.cc b/src/gpu/headless_gpu.cc
index 172a916..c4de577 100644
--- a/src/gpu/headless_gpu.cc
+++ b/src/gpu/headless_gpu.cc
@@ -4,6 +4,7 @@
 #if defined(DEMO_HEADLESS)
 
 #include "gpu.h"
+#include "gpu/effect.h"
 #include "platform/stub_types.h"
 #include <stdio.h>
 
@@ -73,6 +74,10 @@ const GpuContext* gpu_get_context() {
   return &ctx;
 }
 
+WGPUSurface gpu_get_surface() {
+  return nullptr;
+}
+
 #if !defined(STRIP_ALL)
 void gpu_simulate_until(float time, float bpm) {
   (void)time;