App reorganization

app/(app)/create/hooks/useCreateFlowMdUp.ts

@@ -0,0 +1,20 @@
+"use client";
+
+import { useEffect, useState } from "react";
+import { useMediaQuery } from "../../../hooks/useMediaQuery";
+
+/** `--breakpoint-md` (640px); same SSR/first-paint pattern as `useCreateFlowLgUp`. */
+const CREATE_FLOW_MIN_WIDTH_MD = "(min-width: 640px)";
+
+/** True at viewport ≥640px (pairs with Tailwind `md:` on create-flow screens). */
+export function useCreateFlowMdUp(): boolean {
+  const [isMounted, setIsMounted] = useState(false);
+  const isMdOrLarger = useMediaQuery(CREATE_FLOW_MIN_WIDTH_MD);
+
+  useEffect(() => {
+    // eslint-disable-next-line react-hooks/set-state-in-effect -- intentional: defer until mount for SSR/first-paint alignment
+    setIsMounted(true);
+  }, []);
+
+  return !isMounted || isMdOrLarger;
+}