fix(pages): Features nav link navigates to "/" making it indistinguishable from Home

[lizhengfeng101]

Description

Clicking the "Features" (核心特性) navigation tab in the Navbar navigates to /, which is the same route as clicking the logo or landing on the home page. From a user's perspective, if they're already on the landing page, clicking "Features" does nothing visible. If they're on another page (e.g., /docs), clicking "Features" brings them to the home page rather than a dedicated features section.

In contrast, other nav items like "Benchmark" (/benchmark) and "Quick Start" (/quickstart) navigate to distinct routes as expected.

Current behavior:

// pages/src/components/Navbar.tsx:16-22
const navTabs = [
  { path: '/', labelKey: 'navbar.features' },        // ← same as home
  { path: '/benchmark', labelKey: 'navbar.benchmark' },
  { path: '/quickstart', labelKey: 'navbar.quickstart' },
  { path: '/docs', labelKey: 'navbar.docs' },
  { path: '/blog', labelKey: 'navbar.blog' },
];

// pages/src/App.tsx:25
<Route path="/" element={<LandingPage><FeaturesPage /></LandingPage>} />

Expected behavior:

Clicking "Features" should either:

1. Navigate to a dedicated /features route, or
2. Scroll to the features section on the landing page (e.g., via hash /#features)

Scope

• File(s): pages/src/components/Navbar.tsx, pages/src/App.tsx
• Area: SPA routing, navigation UX

Acceptance Criteria

• Clicking "Features" in the navbar produces a visually distinct navigation action (not identical to going to /)
• Active tab highlighting correctly reflects the current page
• All other nav links continue to work as before
• Tests pass (make test)
• Code check passes (make check)

Context

Discovered during review of #487 (code-splitting PR). This issue predates that PR — it exists on main as well. The root cause is that FeaturesPage is embedded directly in the landing page route (/) without its own route or anchor-based scroll target.