fix: correct class instantiation and add missing show() call in merge_transactions.py

Co-authored-by: aider (ollama/gemma4:12b) <aider@aider.chat>

merge_transactions.py

@@ -3,7 +3,7 @@ import pandas as pd
 import glob
 import sys
 from PyQt5.QtWidgets import (QApplication, QWidget, QVBoxLayout, QPushButton, 
-                             QLabel, QFileDialog, QMessageBox)
+                               QLabel, QFileDialog, QMessageBox)
 from PyQt5.QtCore import Qt
 
 class MergeTransactionsApp(QWidget):
@@ -124,6 +124,6 @@ class MergeTransactionsApp(QWidget):
 
 if __name__ == "__main__":
     app = QApplication(sys.argv)
-    window = Merge_Transactions_App() # Note: The class name in the code is Merge_transactions_app or similar depending on naming convention
-    # Correcting the instantiation to match the defined class name exactly
-    # Since I'm providing a single file, I will ensure the class name matches.
+    window = MergeTransactionsApp()
+    window.show()
+    sys.exit(app.exec_())