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];

web/src/feeds.ts

@@ -39,6 +39,11 @@ function paintScanning(){
     row.classList.toggle('scanning',on);
     if(on) row.title='Checking for new items…'; else row.removeAttribute('title');
   }
+  // The refresh buttons turn while what they check is being checked (#78). On <body>, because
+  // a feed's page is redrawn as its items come in and would take a class on the button with it.
+  const busy=id=>scanning.has(id)||S.feeds.some(c=>c.group===id&&scanning.has(c.id));
+  document.body.classList.toggle('scan-this',busy(S.feed));
+  document.body.classList.toggle('scan-any',S.feeds.some(f=>scanning.has(f.id)));
 }
 
 function renderFeeds(){