Add arena/BG opcodes, fix mount speed, buff bar icons, and autorun cancel

Add 36 arena and battleground opcodes with handlers for queue status, team events, invites, and errors. Fix SMSG_FORCE_RUN_SPEED_CHANGE parsing (uint8 not uint32) and remove manual mount speed tracking. Buff bar now shows spell icons and is positioned below the minimap. Both mouse buttons cancel autorun.

src/rendering/camera_controller.cpp

@@ -147,6 +147,9 @@ void CameraController::update(float deltaTime) {
     }
 
     bool mouseAutorun = !uiWantsKeyboard && !sitting && leftMouseDown && rightMouseDown;
+    if (mouseAutorun) {
+        autoRunning = false;
+    }
     bool nowForward = keyW || mouseAutorun || autoRunning;
     bool nowBackward = keyS;
     bool nowStrafeLeft = false;