feat(city): add city landmarks, stores, luminous signs, and ATC echo guard

Add university and fire station civic buildings plus 7 new store types,
each with facade and luminous blade signs. Extend landmark material
colors and sign accents. Fix ATC dispatch to reject prompt-echoing AI
responses via heuristic guard. Add CityPlacesTest for collision and
roadway avoidance, and extend AirportTest and SignLabelsTest.

lang/es.json

@@ -226,6 +226,8 @@
     "city.sign_hospital": "Hospital",
     "city.sign_school": "Escuela",
     "city.sign_cityhall": "Alcaldía",
+    "city.sign_university": "Universidad",
+    "city.sign_firestation": "Cuerpo de Bomberos",
     "city.exercise_need_equipment": "Acérquese a un equipo de la plaza.",
     "city.exercise_need_awake": "Debe estar despierto para ejercitarse.",
     "city.exercise_tired": "Está demasiado cansado para ejercitarse.",