feat(web): object detail + two-pane page + app routing

Implements the navigable SPA shell: object detail pane showing
inventory-minimum fields, flexible fields (via Record<string,unknown>
cast) and visibility badge; ObjectsPage two-pane layout; BrowserRouter
wired through RequireAuth+AppShell; QueryClient provided in main.tsx.
Consolidates ObjectList NavLink to use isActive function form, removing
manual useParams highlight.

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

web/src/objects/objects-page.tsx

@@ -0,0 +1,27 @@
+import { useParams } from "react-router-dom";
+import { useTranslation } from "react-i18next";
+
+import { ObjectList } from "./object-list";
+import { ObjectDetail } from "./object-detail";
+
+export function ObjectsPage() {
+  const { t } = useTranslation();
+  const { id } = useParams();
+
+  return (
+    <div className="grid h-full grid-cols-[20rem_1fr]">
+      <div className="overflow-hidden border-r">
+        <ObjectList />
+      </div>
+      <div className="overflow-hidden">
+        {id ? (
+          <ObjectDetail />
+        ) : (
+          <div className="flex h-full items-center justify-center p-4 text-sm text-neutral-400">
+            {t("objects.selectPrompt")}
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}