The app's own partner counts only come from users who leave the stats on,
so a sponsor's reach and clicks are now also counted where the server sees
them. /api/partners hands out each partner's website and keysUrl (and a
region's) as usemagpie.ai/go/<id>/site|keys[/<region>]; /go sends a
"magpie partner go" event to PostHog (partner, link, region, country) and
302s to partners.js's own URL. One in ten list fetches sends "magpie
partners fetch" with weight 10 while someone is listed. Events carry a
random id each, no install id or address. Ended entries leave the list but
/go still resolves them, since added providers keep the links. Privacy text
updated in README (en, zh), docs/reference.md and the site docs (en, zh, ja).
Run: node --test site/*.test.mjs (27 pass); a scratch copy with a fake
partner served rewritten links, 302'd /go to the real URLs and posted both
events; PostHog's /i/v0/e/ answered 200 to the payload shape.