Wires @tanstack/react-query into every entry and migrates useStatus to
useStatusQuery as the foundation for the multi-page MPA → SPA migration.
- QueryProvider wraps each entry inside ThemeProvider, with devtools gated
on import.meta.env.DEV
- Shared queryClient: 30s staleTime, refetchOnWindowFocus, 1 retry
- useStatusQuery preserves the { status, fetched, refresh } shape so
IndexPage swaps in without further changes
- refetchIntervalInBackground:false stops the 2s status poll when the
panel tab is hidden, cutting idle traffic against the server
