fix(instances): type multiSelectFilter as FilterFn<any> for column reuse

Allows the shared column filter to be attached to typed VMInstance columns
without a FilterFn<unknown> assignability error.

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

frontend/src/components/shared/column-filter.tsx

@@ -21,7 +21,8 @@ declare module '@tanstack/react-table' {
  * of the selected values. Built-in arrIncludesSome expects array cells, so we
  * provide our own. Empty selection passes everything.
  */
-export const multiSelectFilter: FilterFn<unknown> = (row, columnId, value: string[]) => {
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export const multiSelectFilter: FilterFn<any> = (row, columnId, value: string[]) => {
   if (!value?.length) return true;
   return value.includes(String(row.getValue(columnId)));
 };