feat: add waveform cache to avoid re-reading WAV files

sync_audio_test.py

@@ -44,6 +44,7 @@ except ImportError:
     HAS_SD = False
 
 from sync_audio import load_wav, correlate, device_info, lag_to_seconds
+from waveform_cache import cached_load_wav
 
 
 def load_config(path: str) -> dict:
@@ -131,9 +132,9 @@ class SyncWindow(QtWidgets.QMainWindow):
 
         # load
         print(f"Loading {a_path}")
-        self.a, self.sr_a = load_wav(a_path, target_sr=sr)
+        self.a, self.sr_a = cached_load_wav(a_path, target_sr=sr)
         print(f"Loading {b_path}")
-        self.b, self.sr_b = load_wav(b_path, target_sr=sr)
+        self.b, self.sr_b = cached_load_wav(b_path, target_sr=sr)
         # keep originals for lag apply
         self.a_orig = self.a.copy()
         self.b_orig = self.b.copy()