Shane's Trains 0.2.1 - Visual Polish & Motion Fixes — Shane's Trains Steam update #55781

Bug fix - train movement stutter (regression since v0.1.7) Trains at 1x and 5x speeds appeared to "snap forward" every game-minute (~60 wall-seconds at 1x, ~12 seconds at 5x) instead of moving smoothly. The frontend interpolation was gated on the game-minute counter from a pre-lockstep multiplayer design; now refreshes on every tick. - Smooth motion at every speed multiplier. - Backend physics were always correct - this was a frontend display bug only. Saves, economy, signal logic all unaffected by the prior behaviour. - The bug shipped with v0.1.7 when realtime speeds were introduced. Players running at 30x, 60x rarely noticed (game-minute boundary fires every 1-2 seconds); players at 1x, 5x got the worst of it. New - station hierarchy on the map Stations were previously uniform circles regardless of importance. The simulation already knew which were major hubs; the renderer just didn't...