Cloudflare R2 JWT Access (Streaming)

Usage:
GET /<object-key>
Authorization: Bearer <your_jwt>

Token payload example:
{
  "sub": "user123",
  "path": "user123/data.json",
  "exp": <timestamp>
}

The Worker will:
- Verify JWT
- Ensure 'sub' prefix matches object path
- Stream object directly from R2