Remove manual reveal button and fix vote sync on session transitions

Remove the "Reveal Votes" button since auto-reveal handles this. Add
poker:sync event so PokerRoom fetches current vote state on mount,
fixing checkmarks not appearing for other users on subsequent rounds.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/PokerRoom.jsx

@@ -29,6 +29,11 @@ export default function PokerRoom({ session, issue, user, members, roomId, onSav
 
   const socket = useMemo(() => getSocket(), []);
 
+  // Sync current vote state on mount (catches votes cast before this component rendered)
+  useEffect(() => {
+    socket.emit('poker:sync', { sessionId: session.id });
+  }, [session.id, socket]);
+
   useEffect(() => {
     function onVoteUpdate(payload) {
       if (payload.sessionId !== session.id) return;
@@ -82,10 +87,6 @@ export default function PokerRoom({ session, issue, user, members, roomId, onSav
     socket.emit('poker:kick', { roomId, userKey });
   }
 
-  function handleReveal() {
-    socket.emit('poker:reveal', { sessionId: session.id });
-  }
-
   function handleSave() {
     const estimate = Number(manualEstimate || suggestedEstimate);
     if (!Number.isFinite(estimate)) {
@@ -184,14 +185,6 @@ export default function PokerRoom({ session, issue, user, members, roomId, onSav
                   );
                 })}
               </div>
-              {votedUserKeys.length > 0 && (
-                <button
-                  onClick={handleReveal}
-                  className="w-full bg-amber-500 hover:bg-amber-400 text-white font-semibold rounded-sm px-4 py-2 transition-colors cursor-pointer border-none text-sm"
-                >
-                  Reveal Votes ({votedUserKeys.length}/{members.length})
-                </button>
-              )}
             </div>
           )}
         </div>