Time display on InsertOverlay (CanvasLayer 10) shows station local
time (HH:MM), day phase with cycle-tinted color, and day number.
Reads SimulationTime from GameState.game_time via update_from_state().
Adds Constants.format_game_time() helper for testability.
Placeholder layout — position refines when #314 wireframe lands.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>