add password authentication for bot users

tests/test_config.py

@@ -67,5 +67,25 @@ class AssistantModeConfigTests(unittest.TestCase):
             )
 
 
+class PasswordConfigTests(unittest.TestCase):
+    def test_password_is_required(self) -> None:
+        with patch("assistant_bot.config.load_env_file"), patch.dict(
+            os.environ,
+            {},
+            clear=False,
+        ):
+            os.environ.pop(config.PASSWORD_ENV_NAME, None)
+            with self.assertRaises(RuntimeError):
+                config.get_assistant_password()
+
+    def test_password_is_read_from_environment(self) -> None:
+        with patch("assistant_bot.config.load_env_file"), patch.dict(
+            os.environ,
+            {config.PASSWORD_ENV_NAME: "  test-password  "},
+            clear=False,
+        ):
+            self.assertEqual(config.get_assistant_password(), "test-password")
+
+
 if __name__ == "__main__":
     unittest.main()