iOS: presses are felt (#430)

The page asks the app for a haptic ({t:"haptic", kind}) and the app
plays the phone's own. A light tap for play, pause, flag and pull to
refresh; the system's success for marking read, one item or all; its
warning with an error toast. A browser has no host to ask, and an
older app ignores the message, so there is nothing to gate.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/native.ts

@@ -24,6 +24,15 @@ const ipxHost: ((m: any) => void) | null = (() => {
 })();
 
 if (ipxHost) installNativePlayback();
+
+/// A press felt as well as seen, in the app (#430): the phone's haptics, which a page cannot reach.
+/// `tap` for play, pause and the like, `done` for something finished (marked read), `warn` for an
+/// error. An app without them ignores the message; a browser has no host to send it to.
+function haptic(kind: 'tap'|'done'|'warn'){
+  // An error toasted while the script is still loading comes here before this file has declared
+  // ipxHost, which then throws; a haptic is not worth breaking that error's toast for.
+  try{ ipxHost?.({t:'haptic', kind}); }catch{}
+}
 // Here, after ipxHost exists: in the app the button waits for the host to say it has a picker.
 paintRoute();