feat: Add python base project files

These files create a callable Python package and manage the version
number of the complete project in the __about__.py file only. All other
parts, including Makefile, will use that version number.

src/revpi_middleware/__main__.py

@@ -0,0 +1,28 @@
+# -*- coding: utf-8 -*-
+# SPDX-FileCopyrightText: 2025 KUNBUS GmbH
+# SPDX-License-Identifier: GPL-2.0-or-later
+"""Start main application of this package."""
+
+# If we are running from a wheel, add the wheel to sys.path
+if __package__ == "":
+    from os.path import dirname
+    from sys import path
+
+    # __file__ is package-*.whl/package/__main__.py
+    # Resulting path is the name of the wheel itself
+    package_path = dirname(dirname(__file__))
+    path.insert(0, package_path)
+
+if __name__ == "__main__":
+    import sys
+
+    try:
+        # Use absolute import in the __main__ module
+        from revpi_middleware.main_application import main
+
+        # Run the main application of this package
+        sys.exit(main())
+
+    except Exception as e:
+        sys.stderr.write(f"Can not start __main__ module: {e}\n")
+        sys.exit(1)