Dynamic import inside the vi.mock('$entities/Font') factory was missed
when batchFontStore was relocated into its own subdirectory in 1573950.
Restores the previously-failing comparisonStore test suite (9 tests) and
clears the lingering TS error in svelte-check.
Replace hand-rolled async fetching (fetchFontsByIds + isRestoring flag)
with BatchFontStore backed by TanStack Query. Three reactive effects
handle batch sync, CSS font loading, and default-font fallback.
isLoading now derives from batchStore.isLoading + fontsReady.