Correct the Next.js document language and Stage-0 metadata

[Robinlee0929]

Context

The root Next.js layout currently declares lang="zh-Hant" even though the interface content is primarily English. Its metadata also describes “job creation,” while the current Stage-0 interface explicitly presents job creation as unavailable.

Correct language metadata helps assistive technology, browsers, search previews, and portfolio reviewers understand the interface accurately.

Newcomer snapshot

• Difficulty: Beginner
• Scope: Small
• Primary area: TypeScript / Next.js metadata and Vitest regression assertions
• Likely files: app/layout.tsx and components/network/Phase2O04NetworkShell.test.ts
• Python required: Yes
• Node/npm required: Yes
• Physical hardware required: No
• Live device access required: No
• Credentials required: No
• External API/provider required: No
• Task-time network access required: No, after local dependencies are installed
• Start with: npm run test:unit -- components/network/Phase2O04NetworkShell.test.ts
• Before completion: run the issue's full validation sequence, including typecheck, lint, build, full pytest, and report-index
• Do not change: routes, controls, provider access, job creation, command execution, network access, or live-device behavior

Dependency installation may require internet access; the access fields above describe the task after local prerequisites are installed.

Scope

Update only the root document language and public metadata in app/layout.tsx, then add focused regression assertions to the existing network-shell test.

Do not add routes, controls, provider access, job creation, or execution behavior.

Acceptance criteria

• The root <html> element declares the language used by the current interface.
• The metadata description accurately identifies the Next.js application as a secondary Stage-0 evidence/demo surface.
• The metadata no longer implies that job creation is currently available.
• components/network/Phase2O04NetworkShell.test.ts protects the corrected language and metadata.
• Existing routes and Stage-0 safety wording remain unchanged.
• No provider, API, model, job-creation, command, or live-device behavior is introduced.

Suggested starting points

• app/layout.tsx
• components/network/Phase2O04NetworkShell.test.ts
• app/network/layout.tsx for the existing secondary-interface wording

Validation

Run:

• npm run test:unit -- components/network/Phase2O04NetworkShell.test.ts
• npm run typecheck
• npm run lint
• npm run build
• python -m pytest
• python network_lab.py --task report-index

Safety boundary

This is presentation metadata only. It must not add provider access, submission controls, job creation, command execution, network access, or live-device capability.