feat(preload): Make main.py a pointer to the default clock

Signed-off-by: Rahix <rahix@rahix.de>

preload/main.py

+import os
+
+
+def main():
+    # Try loading analog clock
+    default_app = "apps/analog_clock/__init__.py"
+    try:
+        with open(default_app, "r"):
+            pass
+
+        print("main.py: Loading " + default_app)
+        os.exec(default_app)
+    finally:
+        os.exit(1)
+
+
+if __name__ == "__main__":
+    main()