fix(mui): review fixes — Select string contract, DataTable aria-sort, sx/page-clamp/dev-warn

Select value/option restricted to string (MUI sets the literal child value; string|number + onChange:string was a type lie). DataTable sortDirection uses ?? 'asc' so aria-sort is never undefined on the active column. StatusChip sx-merge drops undefined; Pagination clamps page into range; DataTable dev-warns on sortKey without onSort; Alert onClose JSDoc.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/ui/DataTable.tsx

@@ -43,6 +43,9 @@ export default function DataTable<T>({
   sortDir,
   onSort,
 }: DataTableProps<T>) {
+  if (import.meta.env.DEV && columns.some((c) => c.sortKey) && !onSort) {
+    console.warn("DataTable: columns with sortKey require an onSort prop.");
+  }
   if (rows.length === 0 && empty) return <>{empty}</>;
   return (
     <TableContainer sx={{ borderRadius: 2 }}>
@@ -54,7 +57,7 @@ export default function DataTable<T>({
                 key={c.key}
                 align={c.align}
                 sortDirection={
-                  c.sortKey && sortBy === c.sortKey ? sortDir : false
+                  c.sortKey && sortBy === c.sortKey ? (sortDir ?? "asc") : false
                 }
                 sx={{
                   textTransform: "uppercase",