The refresh button turns while its feed is checked (#78)

The feed events already put a spinner on the sidebar row, which a phone
hides. The same state now sets scan-this (the open feed, or a feed in the
open folder) and scan-any (any of your feeds) on <body>, and the refresh
icons turn under them. On <body> because the feed page is redrawn as items
come in.

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

web/src/feedpage.ts

@@ -1,5 +1,6 @@
 /* ---------------- feed page ---------------- */
 function renderFeed(){
+  paintScanning(); // another feed's page may be the one open now
   const box=$('#content');
   box.classList.remove('plain');
   const v=VIEWS[S.feed];