fix: a huge export or list page answers an empty page instead of panicking (WR-14)

(page-1)*perPage overflowed for a large page and sliced out of range.
Export compares the page with the page count before multiplying, and the
list endpoints cap the page number.

controllers/api/auth.go

@@ -184,10 +184,12 @@ func read(ctx context.Context, svc *classes.Service) (*gorm.DB, error) {
 	return svc.DB(ctx)
 }
 
-// The page sizes of the list endpoints.
+// The page sizes of the list endpoints, and the highest page number read
+// (a later page is empty anyway).
 const (
 	defaultPerPage = 50
 	maxPerPage     = 200
+	maxPage        = 1_000_000
 )
 
 // ListInput is the paging and search query every list tool shares.
@@ -206,6 +208,10 @@ func listParams(r *http.Request) ListInput {
 	if in.Page < 1 {
 		in.Page = 1
 	}
+	// (Page-1)*PerPage must not overflow into a negative offset (WR-14).
+	if in.Page > maxPage {
+		in.Page = maxPage
+	}
 	if in.PerPage < 1 {
 		in.PerPage = defaultPerPage
 	}