feat: add multi-device provisioning and local remote-config UI

- add multi-device portal device management, key rotation, and sync request APIs
- add Pi settings UI for remote server URL, device name, and API key
- add local test-connection and sync-now actions
- make upload and config sync reuse dynamic shared credentials
- add Phase 25.5c migration and docs updates

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

tests/test_app_device_config_runtime.py

@@ -1,5 +1,4 @@
 import unittest
-import os
 from unittest.mock import Mock, patch
 
 from modules import app_account, app_car, app_device_sync
@@ -56,16 +55,13 @@ class DeviceSyncReloadCallbackTest(unittest.TestCase):
         finally:
             app_device_sync._RELOAD_CALLBACK = original
 
-    @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):
+    @patch("modules.app_remote_config.server_credentials")
+    def test_sync_credentials_fall_back_to_upload_api_key(self, server_credentials):
+        server_credentials.return_value = {
+            "server_url": "https://example.test",
+            "device_name": "yaris-2013",
+            "api_key": "upload-key",
+        }
         server_url, device_name, device_key = app_device_sync._server_credentials()
 
         self.assertEqual(server_url, "https://example.test")