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/feedpage.ts

@@ -156,7 +156,7 @@ function renderGroup(f,kids){
 }
 
 async function feedAction(a,f){
-  if(a==='scan'){ toast('Scanning '+(f.title||f.id)+'…'); await api('/api/fetch',{method:'POST',body:JSON.stringify({feed:f.id,force:true})}); }
+  if(a==='scan'){ await api('/api/fetch',{method:'POST',body:JSON.stringify({feed:f.id,force:true})}); }
   if(a==='read'){ const r=await api(`/api/feeds/${encodeURIComponent(f.id)}/read-all`,{method:'POST'}); toast(`Marked ${r.marked} read`); await loadFeeds(true); renderFeed(); loadEntries(); }
   if(a==='rm') removeFeed(f);
   if(a==='pin'){