Fix file path bug in resample_audio.py

Changed from os.rename() to shutil.copy2() when creating backups.
This prevents the "No such file or directory" error that occurred
when trying to write the resampled file after the original was renamed.

Now the script:
- Copies original to .backup (instead of renaming)
- Reads from .backup file
- Writes resampled audio to original filename

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

resample_audio.py

@@ -8,6 +8,7 @@ import wave
 import numpy as np
 import os
 import json
+import shutil
 from scipy import signal
 
 def load_config():
@@ -126,16 +127,20 @@ def main():
 
         # Create backup
         backup_path = input_path + '.backup'
+        source_path = input_path
+
         if not os.path.exists(backup_path):
-            os.rename(input_path, backup_path)
+            # Copy to backup instead of rename, so original still exists
+            shutil.copy2(input_path, backup_path)
             print(f"  Backup created: {filename}.backup")
+            source_path = backup_path
         else:
-            input_path = backup_path
             print(f"  Using existing backup")
+            source_path = backup_path
 
         # Resample
         output_path = os.path.join(sounds_dir, filename)
-        if resample_wav(input_path, output_path, target_rate):
+        if resample_wav(source_path, output_path, target_rate):
             print(f"  ✓ Successfully resampled to {target_rate}Hz")
         else:
             print(f"  ✗ Failed to resample, restoring backup")