Improve accuracy of station GPS coordinates

[mattekudacy]

Description

The current station coordinates in [stations.json](https://github.com/mattekudacy/carousel are approximated and may not reflect the exact pickup/dropoff points of each EDSA Carousel station.

Current Problem

• Some stations may trigger detection too early or too late
• Coordinates were initially vibe coded while some are extracted using Google Maps

What's Needed

Community members who regularly ride the EDSA Carousel can help verify and submit accurate GPS coordinates using Google Maps of the 22 stations:

How to Contribute

1. While at a station, note your GPS coordinates (use Google Maps or a GPS app)
2. Submit the station name and coordinates via a Pull Request on stations.json