Playa del Carmen just flipped the switch on a national training push for first responders. The National Firefighters Congress brings more than 600 firefighters, rescuers, and instructors for five days of drills and hard-won lessons. City leaders say the local EMS footprint is bigger and faster now, with more ambulances on the street. What does that look like when the call comes in? New tactics, cross-border instructors, and a focus on human-cente…