Add Arch-based Docker test setup, shallow clone mode support and pkgmgr tests (see ChatGPT conversation: https://chatgpt.com/share/693052a1-edd0-800f-a9d6-c154b8e7d8e0)

tests/test_main.py

@@ -0,0 +1,19 @@
+# tests/test_main.py
+import unittest
+import main
+
+
+class TestMainModule(unittest.TestCase):
+    def test_proxy_commands_defined(self):
+        """
+        Basic sanity check: main.py should define PROXY_COMMANDS
+        with git/docker/docker compose entries.
+        """
+        self.assertTrue(hasattr(main, "PROXY_COMMANDS"))
+        self.assertIn("git", main.PROXY_COMMANDS)
+        self.assertIn("docker", main.PROXY_COMMANDS)
+        self.assertIn("docker compose", main.PROXY_COMMANDS)
+
+
+if __name__ == "__main__":
+    unittest.main()