Add delete button for draft files in case drafts panel

- Add DELETE /api/cases/{case_number}/exports/{filename} endpoint
- Add useDeleteDraft hook in exports API
- Add trash icon + confirmation dialog in drafts panel UI
- Final files (סופי-) cannot be deleted as a safety measure

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web-ui/src/lib/api/exports.ts

@@ -71,6 +71,20 @@ export function useUploadDraft(caseNumber: string) {
   });
 }
 
+export function useDeleteDraft(caseNumber: string) {
+  const qc = useQueryClient();
+  return useMutation({
+    mutationFn: (filename: string) =>
+      apiRequest<{ deleted: boolean; filename: string }>(
+        `/api/cases/${caseNumber}/exports/${filename}`,
+        { method: "DELETE" },
+      ),
+    onSuccess: () => {
+      qc.invalidateQueries({ queryKey: exportsKeys.list(caseNumber) });
+    },
+  });
+}
+
 export function useMarkFinal(caseNumber: string) {
   const qc = useQueryClient();
   return useMutation({