add click and gui pyinstaller targets

src/cmd.py

@@ -1,4 +1,9 @@
+import click
 import carousel
 
-if __name__ == "__main__":
+@click.command()
+def cmd():
     carousel.main()
+
+if __name__ == "__main__":
+    cmd()

src/gui.py

@@ -0,0 +1,10 @@
+from PySide6.QtWidgets import QApplication, QWidget
+import sys
+import carousel
+
+app = QApplication(sys.argv)
+
+window = QWidget()
+window.show()
+
+app.exec()