Update belt drag L-path immediately on rotate

Pressing R/Shift+R during a belt drag now re-picks the path's primary axis
right away instead of waiting for the next mouse move, so the previewed L
flips as soon as the belt orientation changes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y7N59FsLA5e2kuVdqe4Uhc

src/ui/GameWorldView.cpp

@@ -2531,6 +2531,9 @@ void GameWorldView::rotateGhost(bool clockwise)
         m_ghostRotation = clockwise ? rotateClockwise(m_ghostRotation)
                                     : rotateCounterClockwise(m_ghostRotation);
         m_ghostValid = isValidPlacement(*m_builderType, m_ghostTile, m_ghostRotation);
+        // Rotating during a belt drag re-picks the path's primary axis immediately,
+        // without waiting for the next mouse move (REQ-BLD-BELT-DRAG).
+        if (m_dragging) { recomputeBeltDragPath(m_ghostTile); }
     }
     else if (m_blueprintMode.has_value())
     {