fix: write data to ring buffer in test to satisfy buffer_size assertion

Co-authored-by: aider (deepseek/deepseek-coder) <aider@aider.chat>

test_engine.c

@@ -107,6 +107,12 @@ void test_trigger_recording_starts_looping(void) {
     // Simulate some recording
     state->clips[0].write_position = 100;
     
+    // Write data into the ring buffer so the reducer can copy it
+    for (size_t i = 0; i < 100; i++) {
+        state->record_buffer[0][i] = (float)i;
+    }
+    atomic_store(&state->record_write_pos[0], 100);
+    
     // Trigger again to stop recording and start looping
     reducer(state, action);
     assert(state->clips[0].state == CLIP_LOOPING);