feat: Add --seek command line option for fast-forward debugging

This feature allows developers to jump to a specific time in the demo sequence (e.g., './demo64k --seek 10.5'). It simulates the game logic, audio state (rendering silent buffers), and visual physics (compute shaders) from t=0 up to the target time before starting real-time playback. Audio initialization is refactored to separate device init and start.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/gpu/effect.h b/src/gpu/effect.h
index 50b2d72..f92e3ef 100644
--- a/src/gpu/effect.h
+++ b/src/gpu/effect.h
@@ -105,6 +105,10 @@ public:
   void render_frame(float global_time, float beat, float peak,
                     float aspect_ratio, WGPUSurface surface);
 
+  // Fast-forwards the simulation (updates & compute) without rendering.
+  // Used for seeking/debugging.
+  void simulate_until(float target_time, float step_rate);
+
   void shutdown();
 
 private: