Fix matplotlib backend import for PySide6 (Qt6) compatibility

journey_fm_app.py

@@ -24,7 +24,7 @@ from urllib.parse import quote
 import sqlite3
 from datetime import datetime
 import matplotlib.pyplot as plt
-from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
+from matplotlib.backends.backend_qtagg import FigureCanvasQTAgg as FigureCanvas
 from matplotlib.figure import Figure
 
 # Import our existing functionality