fix(src): correct file writing method in process.stft.process_damage_case function to fix incorrect first column name

Closes #104

code/src/process_stft.py

@@ -146,7 +146,7 @@ def process_damage_case(damage_num):
             # Save the aggregated STFT to CSV
             with open(output_file, 'w') as file:
                 file.write('sep=,\n')
-                df_aggregated.to_csv(output_file, index=False)
+                df_aggregated.to_csv(file, index=False)
             print(f"Saved aggregated STFT for Sensor {sensor_num}, Damage {damage_num} to {output_file}")
         else:
             print(f"No STFT data aggregated for Sensor {sensor_num}, Damage {damage_num}.")