Fix student profile dates not saving

Native date pickers blur/refocus the window, which triggered a React Query
refetch mid-edit and wiped the in-progress date. Disable refetchOnWindowFocus,
and make profile/academics edits work on a snapshot with functional state
updates so a background refetch can't clobber input.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/router.tsx

@@ -3,7 +3,14 @@ import { createRouter } from "@tanstack/react-router";
 import { routeTree } from "./routeTree.gen";
 
 export const getRouter = () => {
-  const queryClient = new QueryClient();
+  const queryClient = new QueryClient({
+    defaultOptions: {
+      // Don't refetch when the window regains focus — opening a native date
+      // picker blurs/refocuses the window, which would refetch mid-edit and
+      // wipe in-progress form input.
+      queries: { refetchOnWindowFocus: false },
+    },
+  });
 
   const router = createRouter({
     routeTree,