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/dialogs.ts

@@ -371,7 +371,8 @@ function opmlModal(){
   };
 }
 
-async function scanAll(){ toast('Scanning all feeds…'); await api('/api/fetch',{method:'POST',body:JSON.stringify({force:true})}); }
+// No toast: the spinners on the rows being checked say it (issue #37).
+async function scanAll(){ await api('/api/fetch',{method:'POST',body:JSON.stringify({force:true})}); }
 $('#scanAll').onclick=scanAll;
 $('#prefs').onclick=prefsModal;
 // Someone the proxy signed in is signed out by the proxy: ipx's own sign-out cannot stick while