fix(rto): persist focused contributions immediately after deconstruct success

The successful focused deconstruct calls onFocusedContribution which
updates parent state, but never persisted the new collection to
sessionStorage. This meant an immediate reload would lose the
contribution.

Fix: add a useEffect in ReasoningWorkspace that watches the
focusedContributions prop for changes and saves via the existing
saveSession mechanism. A ref guard prevents double-save alongside the
existing updateStatus-success effect.

components/reasoning-workspace.jsx

@@ -972,6 +972,23 @@ export default function ReasoningWorkspace({
   const [focusedInvestigations, setFocusedInvestigations] = useState({});
   const [focusedAnswer, setFocusedAnswer] = useState("");
 
+  // ── Persist focused contributions immediately after deconstruct success ────
+  const lastPersistedContribCount = useRef(0);
+
+  useEffect(() => {
+    if (!graph) return;
+    if (focusedContributions.length === lastPersistedContribCount.current) return;
+    lastPersistedContribCount.current = focusedContributions.length;
+    saveSession({
+      scenario,
+      situationGraph: graph,
+      selectedQuestion: result?.selectedQuestion,
+      summary: result?.summary || propUnderstanding,
+      updatedAt: new Date().toISOString(),
+      focusedContributions,
+    });
+  }, [focusedContributions]);
+
   function getFocusedInvestigation() {
     if (!focusedPresentationItemId) return null;
     return focusedInvestigations[focusedPresentationItemId] || null;