Staff report: drop unused StaffFileMeta type (YAGNI)

types/form.ts

@@ -382,14 +382,3 @@ export interface StaffReportPayload {
   /** Option-group labels for any select/multiselect/stage field referenced. */
   options: Record<number, SelectOption[]>;
 }
-
-/**
- * Metadata returned by /api/staff/file?id=&key= when called with the JSON
- * Accept header. Not currently used by the UI — the file proxy normally
- * streams bytes — but documented here for future use.
- */
-export interface StaffFileMeta {
-  id: number;
-  fileName: string | null;
-  mimeType: string | null;
-}