Add app icon and update build process

src/main.py

@@ -1,10 +1,28 @@
 
 import sys
+import os
 from PyQt6.QtWidgets import QApplication
+from PyQt6.QtGui import QIcon
 from teletext.ui import MainWindow
 
+def resource_path(relative_path):
+    """ Get absolute path to resource, works for dev and for PyInstaller """
+    try:
+        # PyInstaller creates a temp folder and stores path in _MEIPASS
+        base_path = sys._MEIPASS
+    except Exception:
+        base_path = os.path.abspath(".")
+
+    return os.path.join(base_path, relative_path)
+
 def main():
     app = QApplication(sys.argv)
+    
+    # Set App Icon
+    icon_path = resource_path("app_icon.png")
+    if os.path.exists(icon_path):
+        app.setWindowIcon(QIcon(icon_path))
+        
     window = MainWindow()
     window.show()
     sys.exit(app.exec())