fix: stabilize desktop audio playback

src/native_core/bus.rs

@@ -23,6 +23,7 @@ pub struct NativeBus {
     odd_frame: bool,
     in_vblank: bool,
     frame_complete: bool,
+    cpu_cycles_since_poll: u32,
     mmc3_a12_prev_high: bool,
     mmc3_a12_low_dots: u16,
     mmc3_last_irq_scanline: u32,
@@ -47,6 +48,7 @@ impl NativeBus {
             odd_frame: false,
             in_vblank: false,
             frame_complete: false,
+            cpu_cycles_since_poll: 0,
             mmc3_a12_prev_high: false,
             mmc3_a12_low_dots: 8,
             mmc3_last_irq_scanline: u32::MAX,
@@ -84,6 +86,12 @@ impl NativeBus {
     pub fn clock_cpu(&mut self, cycles: u8) {
         self.clock_cpu_cycles(cycles as u32);
     }
+
+    pub fn take_cpu_cycles_since_poll(&mut self) -> u32 {
+        let cycles = self.cpu_cycles_since_poll;
+        self.cpu_cycles_since_poll = 0;
+        cycles
+    }
 }
 
 // CpuBus trait implementation (memory map + side effects).