Mail: swipe a message left to delete, right to archive. Books: page flip by tap and swipe works on touch screens

The page frame is wider than the screen (pages sit side by side inside it), so tap positions
were measured against the wrong width and taps on touch devices never turned the page.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UaC9HmtHMdRP8dAbN4wAKj

public/sw.js

@@ -1,5 +1,5 @@
 // App-shell cache only; Seafile/API traffic always goes to the network.
-const CACHE = 'hub-v34';
+const CACHE = 'hub-v35';
 const SHARE = 'hub-share'; // files shared into the app from other apps, held until the person picks a folder
 const SHELL = ['/icon.svg', '/manifest.webmanifest', '/icons/icon-192.png', '/icons/apple-touch-icon.png'];