fix: stabilize maintenance flow run/resume and procedural scrolling

frontend/src/pages/MaintenanceFlowDetailPage.tsx

@@ -23,6 +23,11 @@ export default function MaintenanceFlowDetailPage() {
     const load = async () => {
       try {
         const treeData = await treesApi.get(id)
+        if (treeData.tree_type !== 'maintenance') {
+          toast.error('This page is only for maintenance flows')
+          navigate('/trees?type=maintenance')
+          return
+        }
         setTree(treeData)
 
         // Load recent sessions for this tree