Highlight tunnel connections in green when selected

src/ui/GameWorldView.h

@@ -1,9 +1,11 @@
 #pragma once
 
+#include <map>
 #include <optional>
 #include <random>
 #include <set>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include <QElapsedTimer>
@@ -42,6 +44,7 @@
 #include "Rotation.h"
 #include "Tick.h"
 #include "TickDriver.h"
+#include "TunnelCompletion.h"
 #include "VisualsConfig.h"
 
 struct Command;
@@ -214,6 +217,12 @@ private:
     // Recomputes m_tunnelGhostType and m_tunnelPartnerTile from the current ghost
     // tile, rotation, and sub-tile cursor position. Only meaningful in tunnel mode.
     void         updateTunnelGhost();
+    // Indexes every tunnel entry/exit — built or still a construction site — by its
+    // single-cell tile. Shared by the placement preview and the selection highlight.
+    std::map<std::pair<int, int>, TunnelTileInfo> collectTunnelTiles() const;
+    // Draws the green connection highlight for every selected tunnel end that has a
+    // matching end (REQ-BLD-TUNNEL-SELECT-HIGHLIGHT).
+    void         drawSelectedTunnelConnections(QPainter& painter);
 
     // Belt drag placement (REQ-BLD-BELT-DRAG).
     // Per-path-tile decision, shared by ghost drawing and release-time placement.