refactor(font): keep @tanstack out of the entity public API barrel

Extract NonRetryableError into its own tanstack-free module and drop the
./api re-export from the Font slice barrel. Importing $entities/Font no
longer transitively loads @tanstack/query-core or constructs the QueryClient
singleton via the ./api and ./lib (errors) chains — light consumers (domain,
types, consts) and unit specs stop paying for TanStack.

Note: ./ui still pulls the stores; addressed separately.

src/entities/Font/lib/errors/errors.ts

@@ -1,4 +1,4 @@
-import { NonRetryableError } from '$shared/api/queryClient';
+import { NonRetryableError } from '$shared/api/nonRetryableError';
 
 /**
  * Thrown when the network request to the proxy API fails.