fix: Suppress bestClosedNode oscillation during exploratory retry cooldown

When normal A* exhausts its node budget and triggers an exploratory retry,
a short partial path is built toward the goal.  Once that path is consumed
(typically in 1-2 frames), the next A* call during the cooldown window
previously fell through to bestClosedNode, which pointed in a different
direction (toward open space), causing visible 1-tile back-and-forth
oscillation in congested narrow corridors.

Now, when we are still in cooldown for the same destination, we return
tsBlocked instead of emitting a bestClosedNode path.  The unit waits
until the cooldown expires and a fresh exploratory retry fires.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: andy5995

source/glest_game/ai/path_finder.cpp

@@ -856,6 +856,17 @@ TravelState PathFinder::aStar(Unit *unit, const Vec2i &targetPos, bool inBailout
                     }
 
                     return aStar(unit, targetPos, false, frameIndex, pathFindNodesExploratoryMax, nullptr, 0.25f, true);
+                } else if (unit->getLastPathfindFailedPos() == finalPos) {
+                    // Still in cooldown for this destination.  Using bestClosedNode
+                    // here would give a partial path in the wrong direction (toward
+                    // open space rather than around the obstacle), causing visible
+                    // back-and-forth oscillation.  Return tsBlocked so the unit
+                    // waits until the cooldown expires and a fresh exploratory retry
+                    // can fire.
+                    if (frameIndex < 0) {
+                        path->incBlockCount();
+                    }
+                    return tsBlocked;
                 }
             }
         } else {