This replaces the standalone API request functions with an NmdcServerClient class with equivalent methods. A singleton instance of this class is constructed and exported. This allows an API token to be set on this instance and all subsequent requests will use that token.

These changes also add a new method for calling the `/api/me` endpoint to retrieve the current user.

The Login page has a button that initiates the nmdc-server login using the @capacitor/browser plugin and a new environment variable for the server login route.

The Token page is where the backend will redirect to on successful login with the API token in a query parameter. This page collects that token, places it in persistent storage, and redirects to the home page.

The Logout page clears the token from persistent storage and redirects to the root page.

These changes wrap the main application in the new StoreProvider. The TanStack query setup has also been moved to a dedicated component so that it can use the `useStore` hook to access the store while setting up its persistence layer. Finally, the routing has also moved to a separate component where it also uses the `useStore` hook in order to decide where to redirect the root route.

A new AuthRoute component has been added that can be used when registering routes that a user must be logged in (as determined by having an API token in the store) to view.

This is mainly for demo purposes and can be removed later