fix: disable Python garbage collector to prevent 1s periodic audio pops

Default GC threshold (700 allocs) triggers ~every 1.4s in the
real-time audio callback due to ~500 numpy allocs/sec. Each GC
pause (10-50ms) exceeds the 5.3ms callback window at 256/48k,
producing audible pops at ~1Hz intervals.

Reference counting handles 99% of object cleanup — GC only handles
cyclic garbage. Disabling it is safe for a process that exits cleanly
(os reclaims everything).

main.py

@@ -838,7 +838,18 @@ def main() -> int:
     except Exception as exc:
         logger.warning("Could not set CPU governor (non-root?): %s", exc)
 
-    import argparse
+    # Disable Python garbage collector to prevent 10-50ms GC pauses in
+    # the real-time audio callback. At ~500 numpy allocs/sec in the
+    # pipeline, default GC (threshold=700) triggers every ~1.4s,
+    # causing audible pops. Reference counting handles 99% of cleanup.
+    try:
+        import gc
+        gc.disable()
+        logger.info("GC disabled for RT audio stability")
+    except Exception as exc:
+        logger.warning("Could not disable GC: %s", exc)
+
+    logger.info("Pedal v2 starting up...")
 
     parser = argparse.ArgumentParser(
         description="Pi Multi-FX Pedal — real-time guitar multi-effects",