Add authentication infrastructure for protected routes:
- withAuth() wrapper for API route handlers (src/lib/auth-middleware.ts)
- Next.js middleware for page protection (src/middleware.ts)
withAuth() loads auth from cookies, validates session, and passes
user context to handlers. Returns 401 for unauthenticated requests.
Page middleware redirects unauthenticated users to /login, while
allowing public routes (/login), API routes (handled separately),
and static assets through.
Tests: 18 new tests (6 for withAuth, 12 for page middleware)
Total test count: 60 tests passing
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
