fix: resolve stale closure causing breadcrumbs to disappear on back-navigation (closes #2)

The onClick handler in createPathSegment closed over the graphsPath variable
from the render when the segment was created. By the time a breadcrumb was
clicked (after further navigation), that closure was stale, so findIndex
returned -1 and splice(0) wiped the entire breadcrumb array.

Fix: use the functional updater form of setGraphsPath so findIndex runs
against the current state rather than a stale snapshot.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/Graph.tsx

@@ -264,12 +264,7 @@ const Graph = forwardRef<GraphHandle, { setGraphPath: React.Dispatch<React.SetSt
       title: selectedNodeName,
       key: pathSegmentId,
       onClick: () => {
-        const index = graphsPath.findIndex(p => p.key === pathSegmentId);
-        setGraphsPath(prev => {
-          prev.splice(index + 1);
-
-          return [...prev];
-        });
+        setGraphsPath(prev => prev.slice(0, prev.findIndex(p => p.key === pathSegmentId) + 1));
         selectGraphId(pathSegmentId);
       }
     } as BreadcrumbItemType;