feat: continuous pulse glow when lobby is full, add horizontal offset for player list

Make the header meter pulse animation loop indefinitely (1.2s
ease-in-out) while playerCount equals maxPlayers. Stops when a
player leaves. Also add horizontal offset control for the player
list positioning.

Made-with: Cursor

optimized-controls.html

@@ -52,7 +52,7 @@
         }
 
         #header.meter-full-pulse {
-            animation: meter-full-pulse 0.6s ease-out;
+            animation: meter-full-pulse 1.2s ease-in-out infinite;
         }
         
         #footer {