feat(Core/Movement): port smooth waypoint movement from Cataclysm Preservation Project (#25106)

Co-authored-by: blinkysc <blinkysc@users.noreply.github.com>
Co-authored-by: Ovahlord <dreadkiller@gmx.de>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Kitzunu <Kitzunu@users.noreply.github.com>

src/server/scripts/World/npcs_special.cpp

@@ -1356,6 +1356,7 @@ public:
             }
         }
 
+        using CreatureAI::WaypointReached;
         void WaypointReached(uint32 /*waypointId*/) override
         {
         }