Cleanup: Remove Leaflet, replace with LngLatTuple in [lng, lat] order

[Copilot]

Leaflet was only remaining in the codebase as type imports (LatLngTuple, LatLngExpression). This removes the packages entirely and introduces a proper LngLatTuple type aligned with GeoJSON/MapLibre convention.

Type replacement

Added to src/app/types.ts:

/** [longitude, latitude] — GeoJSON / MapLibre GL convention */
export type LngLatTuple = [number, number];

Replaces LatLngTuple / LatLngExpression from leaflet across 8 files.

Coordinate order fix (bonus)

Leaflet stored coordinates as [lat, lng]; GeoJSON/MapLibre expects [lng, lat]. All bounding-box creation sites now emit [lng, lat] directly:

• getBoundingBox / selectFeedBoundingBox / selectBoundingBoxFromLatestDataset / computeBoundingBox — swapped to [lng, lat]
• getBoundsFromCoordinates — destructures ([lng, lat]) instead of ([lat, lng])
• Map.tsx — removed the [p[1], p[0]] coordinate swap; polygon data is now in the correct format at the source

Package removal

Removed leaflet, @types/leaflet, and react-leaflet from package.json and dropped the jest.mock('react-leaflet', () => ({})) stub from setupTests.ts.

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Cleanup: Remove Leaflet and replace it's types</issue_title>
<issue_description>With the migration to Nextjs, leaflet has been replaced in favor of maplibre

the only remains of it in our code base is used as types

import { type LatLngExpression } from 'leaflet';

remove this and find an alternative

bonus: reorganize the datastructure of how we store our polygons for less transformations</issue_description>

Comments on the Issue (you are @copilot in this section)

@ianktc Possibly https://maplibre.org/maplibre-gl-js/docs/API/classes/LngLat/ @Alessandro100 It's the same concept, but different data structure. See image

The real data structure resembles leafletLngLat, there is a possibility that we could reorganize it to fit the new maplibre one, but ideally not (if existing functionality works, we shouldn't touch it). Requires some research</comment_new>

• Fixes Cleanup: Remove Leaflet and replace it's types #35

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Project	Deployment	Actions	Updated (UTC)
mobilitydatabase-web	Ready	Preview, Comment	Mar 11, 2026 0:43am

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[github-actions]

*Lighthouse ran on https://mobilitydatabase-8ffnh0ow9-mobility-data.vercel.app/ * (Desktop)
⚡️ HTML Report Lighthouse report for the changes in this PR:

Performance	Accessibility	Best Practices	SEO
🟢 100	🟢 96	🟢 100	🟢 100

*Lighthouse ran on https://mobilitydatabase-8ffnh0ow9-mobility-data.vercel.app/feeds * (Desktop)
⚡️ HTML Report Lighthouse report for the changes in this PR:

Performance	Accessibility	Best Practices	SEO
🟠 89	🟠 87	🟢 96	🟢 100

*Lighthouse ran on https://mobilitydatabase-8ffnh0ow9-mobility-data.vercel.app/feeds/gtfs/mdb-2126 * (Desktop)
⚡️ HTML Report Lighthouse report for the changes in this PR:

Performance	Accessibility	Best Practices	SEO
🔴 38	🟢 94	🟢 96	🟢 100

*Lighthouse ran on https://mobilitydatabase-8ffnh0ow9-mobility-data.vercel.app/feeds/gtfs_rt/mdb-2585 * (Desktop)
⚡️ HTML Report Lighthouse report for the changes in this PR:

Performance	Accessibility	Best Practices	SEO
🟢 100	🟠 83	🟢 100	🟢 100

*Lighthouse ran on https://mobilitydatabase-8ffnh0ow9-mobility-data.vercel.app/feeds/gbfs/gbfs-flamingo_porirua * (Desktop)
⚡️ HTML Report Lighthouse report for the changes in this PR:

Performance	Accessibility	Best Practices	SEO
🟠 88	🟢 94	🟢 96	🟢 100

[Alessandro100]

Tested with:

https://mobilitydatabase-web-git-copilot-cleanup-r-ada8aa-mobility-data.vercel.app/feeds/gtfs/mdb-437

could not find a valid gbfs feed on preview env -> tested locally

[Alessandro100]

tested and works well