RapidTunnel basic telemetry endpoint

This endpoint receives anonymous product health events from the
RapidTunnel website and app. It accepts only a fixed catalog of categorical
events (for example "voucher checkout created: ok"). The catalog is published at
/v1/contract.

It does not accept or forward account identifiers, voucher codes, payment
details, URLs, free-form text, or VPN traffic information. Events are validated,
stripped of connection metadata, and forwarded to our analytics processor
(PostHog) with person profiles, IP capture, and GeoIP disabled.

This edge service necessarily receives your network connection in order to
answer the request. It does not store or forward your IP address.