Run lobbies' games on the server

The server now runs every lobby's sandbox and queued games as rooms, stepped at
the tick rate on one thread. Players send controls ahead of time, late ones repeat
their last, and everyone in a room gets back the controls it played, its events
and checksums. Games start from sandbox queues, players return when they leave,
and play-again moves them to a fresh room. Protocol version 3.

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

src/sim.cpp

@@ -73,6 +73,24 @@ void Sim::game_start(Match& lobby, const int* members, int count, const Rules& r
     match.start(*this);
 }
 
+void Sim::event_apply(const RoomEvent& event)
+{
+    if (event.type == ROOM_JOIN)
+        match.member_join(*this, event.member, event.profile);
+    if (event.type == ROOM_LEAVE)
+        match.member_leave(*this, event.member);
+    int index = match.fighter_find(*this, event.member);
+    if (index < 0)
+        return;
+    if (event.type == ROOM_QUEUE)
+        match.queue_open(*this, index, event.rules);
+    if (event.type == ROOM_UNQUEUE)
+    {
+        match.queues[index].isActive = false;
+        match.isQueueReady[index] = false;
+    }
+}
+
 // Moves a level by a step within the levels there are, cueing whether it went up or down.
 void level_step(Sim& sim, int& level, int step)
 {