panel: disable demote and delete for the only global admin

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/web/handlers/handlers_users.go

@@ -132,9 +132,18 @@ func (h *Handlers) renderUserForm(w http.ResponseWriter, r *http.Request, status
 	data["FormDomains"] = view.FormDomains
 	data["FormPassword"] = view.FormPassword
 	data["IsEdit"] = userID != 0
+	data["LastGlobalLocked"] = lastGlobalLocked(h, userID, view.FormRole)
 	h.view.Render(w, status, "user_form", data)
 }
 
+func lastGlobalLocked(h *Handlers, userID int64, formRole string) bool {
+	if userID == 0 || formRole != string(store.RoleGlobal) {
+		return false
+	}
+	n, err := h.store.CountGlobalUsers()
+	return err == nil && n <= 1
+}
+
 func (h *Handlers) submitUserCreate(w http.ResponseWriter, r *http.Request) {
 	if err := r.ParseForm(); err != nil {
 		h.renderUserForm(w, r, http.StatusBadRequest, 0, userFormView{FormErr: "Invalid form submission."})