Fix auto-attack stalling after SMSG_ATTACKSTOP and remove stale comments

Re-send CMSG_ATTACKSWING every second while auto-attacking so combat
resumes automatically when the server pauses the attack loop (out of
range, etc). Previously the client kept autoAttacking=true but never
re-engaged, requiring the player to manually right-click again.

Also remove leftover single-player/offline references from comments.

include/game/transport_manager.hpp

@@ -43,7 +43,7 @@ struct ActiveTransport {
     glm::mat4 transform;        // Cached world transform
     glm::mat4 invTransform;     // Cached inverse for collision
 
-    // Player attachment (single-player for now)
+    // Player attachment state
     bool playerOnBoard;
     glm::vec3 playerLocalOffset;