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/app.tsx

@@ -1,3 +1,24 @@
+import { BrowserRouter, Navigate, Route, Routes } from "react-router-dom";
+
+import { RequireAuth } from "./auth/require-auth";
+import { LoginPage } from "./auth/login-page";
+import { AppShell } from "./shell/app-shell";
+import { ObjectsPage } from "./objects/objects-page";
+
 export function App() {
-  return <h1>Collection</h1>;
+  return (
+    <BrowserRouter>
+      <Routes>
+        <Route path="/login" element={<LoginPage />} />
+        <Route element={<RequireAuth />}>
+          <Route element={<AppShell />}>
+            <Route path="/objects" element={<ObjectsPage />} />
+            <Route path="/objects/:id" element={<ObjectsPage />} />
+            <Route path="/" element={<Navigate to="/objects" replace />} />
+          </Route>
+        </Route>
+        <Route path="*" element={<Navigate to="/objects" replace />} />
+      </Routes>
+    </BrowserRouter>
+  );
 }