feat(frontend): optimize bundle size with dynamic imports and route-based code splitting

[Agbasimere]

Description

This PR implements dynamic imports, route-based code splitting, and lazy loading for non-critical features (AR/VR, Metaverse, Lab, and BCI) to optimize the initial page load bundle sizes.

Key Changes

1. Removed Custom splitChunks Overrides: The previous config forced all of node_modules into a single shared vendors.js chunk, bloating every route to 1.61 MB. Reverting to Next.js's defaults restored optimal code splitting.
2. Web-Vitals & Performance Monitor Isolation: Created PerformanceInitializer.tsx to lazy load performance-monitor on client-side mount, keeping it out of the server rendering path.
3. Dynamic Module Entry Points: Exported all heavy modules (AR/VR, Metaverse, Lab, BCI) using next/dynamic with ssr: false in their folder index files:
   • ARVR index.ts
   • Metaverse index.ts
   • Lab index.ts
   • BCI index.ts
4. Official @next/bundle-analyzer Wrapper: Added it to package.json and configured next.config.js to avoid duplicate bundle reports.

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Verification Results

• First Load JS shared by all app router pages: Reduced from 1.61 MB to 88.2 kB.
• Landing Page Initial Bundle Size: ~100 KB gzipped (512 kB raw, including the root Web3 provider).
• Three.js, D3, and TensorFlow: Successfully code-split and only loaded when navigating to /campus, /lab, and /bci-dashboard respectively.
• Unit Tests: ErrorBoundary and RouteErrorBoundary test suites ran and passed successfully (59/59 passed).

Closes #73