Frontend: Canonical React + Vite app foundation

[Abiorh001]

Parent: #29

Why

The repo currently has only demos/week1_api_demo_ui, and README.md says that UI is temporary, not the canonical Workstream frontend. The architecture locks the frontend as React + Vite + TypeScript internal operations UI.

Roadmap Source

• AGENTS.md: frontend locked as React + Vite + TypeScript
• README.md: Week 1 API Demo UI is temporary
• docs/architecture_system_architecture.md: React + Vite owns the internal operations UI
• docs/roadmap_30_day_master_plan.md: dashboards and review UI after backend contracts stabilize

Scope

• Decide canonical frontend location/package structure.
• Scaffold production-oriented React + Vite + TypeScript app or promote/refactor the demo only if that is explicitly chosen.
• Add API client/auth-token handling for existing Flow-style backend auth.
• Add route/layout foundation for project manager, worker, reviewer, admin/finance surfaces.
• Keep it operations/workflow focused, not a marketing page.

Acceptance Criteria

• Canonical frontend app builds with TypeScript.
• It can call /api/v1/health and /api/v1/auth/me against the backend.
• App shell includes navigation placeholders for project setup, task queue, worker tasks, review queue, dashboards.
• Demo UI remains clearly separated or is retired intentionally.
• README/docs are updated to show how to run the canonical frontend.

Contributor Fit

Primary frontend starter issue for a contributor with maintainer review.