feat(highlights): add click-to-rebroadcast functionality to relay indicator

Make relay indicator icons clickable to trigger manual rebroadcast to all connected relays:
- Click plane icon (local/offline) to rebroadcast to remote relays
- Click server icon to rebroadcast to all relays
- Show spinner while rebroadcasting
- Update icon from plane to server on successful rebroadcast
- Keep plane icon on failure
- Pass relayPool and eventStore through component chain
- Add local state management for highlight updates in HighlightsPanel
- Enhance CSS with scale animation on hover/active

src/components/ThreePaneLayout.tsx

@@ -140,6 +140,8 @@ const ThreePaneLayout: React.FC<ThreePaneLayoutProps> = (props) => {
             highlightVisibility={props.highlightVisibility}
             onHighlightVisibilityChange={props.onHighlightVisibilityChange}
             followedPubkeys={props.followedPubkeys}
+            relayPool={props.relayPool}
+            eventStore={props.eventStore}
           />
         </div>
       </div>