Track each feature as its own Plausible event

Send 'click: pause', 'click: skip', etc. instead of a generic
'feature_click' so each feature gets its own Goal in Plausible.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

public/app.js

@@ -280,7 +280,7 @@ function PayPlay() {
   }, [flash]);
 
   const tryAct = (k, fn) => {
-    track("feature_click", { feature: k, subscribed: !!has(k) });
+    track("click: " + k, { subscribed: !!has(k) });
     if (has(k)) { fn(); return; }
     setModal({ key: k, action: fn });
     setModalPhase("choose");