fix: authenticate device config sync like upload client

- send X-Device-Name and X-Api-Key to /api/device-config
- require YARIS_DEVICE_NAME alongside shared upload creds
- fix server create_device output to match actual Pi env names
- document shared upload/config sync credential requirements

Co-authored-by: Copilot <[email protected]>

tests/test_app_device_config_runtime.py

@@ -56,11 +56,20 @@ class DeviceSyncReloadCallbackTest(unittest.TestCase):
         finally:
             app_device_sync._RELOAD_CALLBACK = original
 
-    @patch.dict(os.environ, {"YARIS_SERVER_URL": "https://example.test", "YARIS_API_KEY": "upload-key"}, clear=True)
+    @patch.dict(
+        os.environ,
+        {
+            "YARIS_SERVER_URL": "https://example.test",
+            "YARIS_DEVICE_NAME": "yaris-2013",
+            "YARIS_API_KEY": "upload-key",
+        },
+        clear=True,
+    )
     def test_sync_credentials_fall_back_to_upload_api_key(self):
-        server_url, device_key = app_device_sync._server_credentials()
+        server_url, device_name, device_key = app_device_sync._server_credentials()
 
         self.assertEqual(server_url, "https://example.test")
+        self.assertEqual(device_name, "yaris-2013")
         self.assertEqual(device_key, "upload-key")