A spinner on the feed being checked, not toasts; check only your own feeds

The scan's events reach everyone, so every browser showed "<feed>: N new" and
"Scanning…" toasts, and refreshed, for everyone's feeds. Now a feed's row, and
its folder's, carries a spinner between feed_start and its done, skip or error;
the list refreshes only for the reader's own feeds; the scan toasts are gone, and
"Downloaded" is said only for a file on screen.

"Check every feed" from the web UI sent a scan of every feed on the server.
Command::Fetch takes an optional `feeds` list -- those feeds and the feeds
inside any OPML among them -- and the web fills it with the asker's
subscriptions. The schedule and the CLI send none, meaning every feed.

Closes #37.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

web/src/feeds.ts

@@ -25,6 +25,22 @@ const VIEWS={
     blurb:'Episodes you started and have not finished, across every feed you subscribe to. Pick one up where you left off.'},
   ':all':{title:'All Subscriptions',icon:ICON.all},
 };
+/// Feeds being checked right now, from the event stream: their rows, and the row of a folder
+/// holding one, carry a spinner.
+const scanning=new Set<string>();
+function setScanning(id: string, on: boolean){
+  if(on) scanning.add(id); else scanning.delete(id);
+  paintScanning();
+}
+function paintScanning(){
+  for(const row of $$('#feedlist .feed')){
+    const id=row.dataset.id;
+    const on=scanning.has(id)||S.feeds.some(c=>c.group===id&&scanning.has(c.id));
+    row.classList.toggle('scanning',on);
+    if(on) row.title='Checking for new items…'; else row.removeAttribute('title');
+  }
+}
+
 function renderFeeds(){
   const q=$('#feedFilter').value.trim().toLowerCase();
   const list=$('#feedlist'); const top=list.scrollTop;
@@ -104,6 +120,7 @@ function renderFeeds(){
     if(kids) $('.chev',el).onclick=ev=>{ ev.stopPropagation(); toggleGroup(f.id); };
     list.appendChild(el);
   }
+  paintScanning();
   done();
 }
 function selectFeed(id){