Simplify: Remove redundant round-label from timeline

The round-label was redundant since we already have 'Round N' displayed
in the progress section. Keeping just the round number (1, 2, 3...) in
the timeline entries for a cleaner, less cluttered UI.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

frontend/src/components/TimelinePanel.vue

@@ -36,7 +36,6 @@ const totalRounds = computed(() => conversationHistory.value.length)
       >
         <div class="entry-header">
           <div class="round-number">{{ index + 1 }}</div>
-          <div class="round-label">Round {{ round.roundNumber }}</div>
         </div>
 
         <!-- Agent status for this round -->
@@ -134,12 +133,6 @@ const totalRounds = computed(() => conversationHistory.value.length)
   color: white;
 }
 
-.round-label {
-  font-size: 0.875rem;
-  font-weight: 600;
-  color: rgba(255, 255, 255, 0.9);
-}
-
 .agent-list {
   display: flex;
   gap: 0.4rem;