refactor(expo): move pk change reset to useEffect

Move publishable key hot-swap ref reset into a useEffect with pk in
the dependency array. Removes the prevPkRef manual comparison.

Author: chriscanin

packages/expo/src/provider/ClerkProvider.tsx

@@ -68,15 +68,12 @@ export function ClerkProvider<TUi extends Ui = Ui>(props: ClerkProviderProps<TUi
   const pendingNativeSessionRef = useRef<string | null>(null);
   const initStartedRef = useRef(false);
   const sessionSyncedRef = useRef(false);
-  const prevPkRef = useRef(pk);
-
   // Reset refs when publishable key changes (hot-swap support)
-  if (prevPkRef.current !== pk) {
-    prevPkRef.current = pk;
+  useEffect(() => {
     pendingNativeSessionRef.current = null;
     initStartedRef.current = false;
     sessionSyncedRef.current = false;
-  }
+  }, [pk]);
 
   // Get the Clerk instance for syncing
   const clerkInstance = isNative()