trufi-association/trufi-core ? reverse-engineered prompt

Build me a Flutter app for public transportation that can be used as the base for a city transit app.

I want the app to let people search for a start and destination, plan routes with transit, walking, and biking, show live vehicle positions when available, and guide the rider turn by turn. It should also have saved places, fares, feedback, settings, and an about screen, plus a map view with points of interest and a clean app shell that feels ready for real world use.

Please make it work as a reusable core so different city apps can plug in their own data and routing setup, with an example app wired up end to end. Use the existing open data approach, support online and offline place search, and make the code structure easy to extend for more screens and map providers. If anything is unclear, look up the current docs online and follow the patterns already used in the project.