Update preference normalization logic to explicitly reject arrays when
validating record types, ensuring only plain objects are accepted. Adjust
ConfigProvider effect conditions for clarity and correctness. Add unit tests
verifying that arrays are not accepted as valid preference records or saved
voices.
Move provider normalization logic into a dedicated module to ensure consistent
handling of provider defaults and user preference inheritance across client and
server. Update layout components to mount ConfigProvider only at the shared
layout level, preventing unnecessary remounts and hydration issues during
navigation. Adjust app config defaults so user provider settings are empty by
default, always inheriting the admin-configured provider unless explicitly set.
Add tests for normalization and sync logic to ensure robust provider resolution.
