Page: catch background fetches, no HTML in errors, a trace ends after a quiet minute (#219)

The page reported NetworkError rejections from the live update's list refresh and the first
feed load, which had no catch, whenever the network was gone (a laptop asleep). A Cloudflare
502 page became a request's error message, since api() used whatever body came back. And
the trace id lived until the next tap, so background requests nine hours apart shared one
trace. The id now ends after a minute without a request; a play's position saves, every ten
seconds, keep it going.

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

web/src/events.ts

@@ -15,7 +15,8 @@ function connect(){
   // Back after a drop: whatever was sent meanwhile went to nobody.
   sse.onopen=()=>{ if(dropped){ dropped=false; catchUp(); } };
   const soon=(fn,ms=500)=>{ let t; return ()=>{ clearTimeout(t); t=setTimeout(fn,ms); }; };
-  const refreshEntries=soon(()=>{ if(S.feed) loadEntries(); });
+  // Caught: a network gone when one fires (a laptop asleep) was an unhandled rejection (#219).
+  const refreshEntries=soon(()=>{ if(S.feed) loadEntries().catch(()=>{}); });
   // Every scan's events reach everyone; only this person's feeds are theirs to show or refresh.
   const mine=id=>S.feeds.some(f=>f.id===id);
   sse.onmessage=m=>{
@@ -70,4 +71,4 @@ function connect(){
   sse.onerror=()=>{ sse.close(); dropped=true; setTimeout(connect,4000); };
 }
 connect();
-loadFeeds();
+loadFeeds().catch(()=>{});