Feature: Tankerkönig API integration for live German fuel prices

[dannymcc]

Summary

Tankerkönig is a German open data service (CC license) that provides live fuel prices for petrol stations across Germany. Integrating this API would allow German users to pull current fuel prices directly into May's stations feature.

Use Case

German users could select their favourite stations and have current fuel prices automatically populated, rather than entering them manually. This is similar to integrations already used in German home automation systems.

API Details

• API documentation: https://creativecommons.tankerkoenig.de
• Free to use under Creative Commons license
• Provides prices for nearby stations based on location/radius or by station ID

Scope

• Add Tankerkönig API key setting to app settings
• Allow stations to be linked to a Tankerkönig station ID
• Periodically fetch and display current prices for linked stations

Notes

Raised via user feedback from a German self-hosted deployment.

[mattradford]

This may require a re-think of how stations and cheapest fuel works. Numerous countries have fuel price APIs, such as the UK's Fuel Finder. Would stations need a unique ID per API / country?

Using these APIs to find nearest cheapest fuel opens up more questions? What about finding other services at those stations? Would we want to filter by fuel / charging? Or 24h service?

@dannymcc If you're open to this sort of integration, perhaps we could discuss here what this would look like. Do you have a roadmap in mind, BTW?

Also: very cool - https://www.fuelinsight.co.uk/