Lets an operator load and update fee_address/bet_amount_sats from a
form (using the X-Admin-Token header) instead of curl/Swagger, with
inline status feedback and the same request/response log as the rest
of the page.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Single-page vanilla HTML/JS frontend (register/login, balance,
place bet, withdraw) served by FastAPI at the same origin so it can
exercise the live API without CORS setup. Manual-testing aid only,
not part of the MVP spec.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>