refactor(map): report the GL viewport from a module of its own

reportGlViewport says what a GL map shows, its bounds and its zoom on the
raster tile scale, and has its own test for that scale. MapViewGL only
wires it to moveend and idle, and its test checks that wiring. The GL map
tests put the zoom back to its default before each test, as they do for
every other value a test overrides, instead of each test restoring it.

client/src/components/Map/MapViewGL.tsx

@@ -8,7 +8,8 @@ import { renderIconMarkup } from '../../utils/iconMarkup'
 import type mapboxgl from 'mapbox-gl'
 import { useSettingsStore } from '../../store/settingsStore'
 import { useTranslation } from '../../i18n/TranslationContext'
-import { applyBaseLayer, rasterTileZoom } from './glRasterLayers'
+import { applyBaseLayer } from './glRasterLayers'
+import { reportGlViewport } from './glViewport'
 import { isTourLayerHit, useTourMapLayersGL } from './mapRasterOverlay'
 import { MapLayerSwitcher, TourMapLayerSwitcher, MAP_LAYER_SWITCHER_INSET, type BaseLayer, type TourBaseLayer } from './MapLayerSwitcher'
 import { MapLockPill } from './MapLockPill'
@@ -1432,15 +1433,8 @@ export function MapViewGL({
       if (isTourLayerHit(map, e.point)) return // a picked via ferrata or paddle obstacle opens its card instead
       onClickRefs.current.map?.({ latlng: { lat: e.lngLat.lat, lng: e.lngLat.lng } })
     })
-    // Emit the viewport bbox (pan/zoom + once on first idle) so the POI-explore
-    // pill can fetch OSM places for the visible area, with the zoom on the raster tile scale.
-    const emitViewport = () => {
-      const b = map.getBounds()
-      onViewportChangeRef.current?.(
-        { south: b.getSouth(), west: b.getWest(), north: b.getNorth(), east: b.getEast() },
-        rasterTileZoom(map.getZoom()),
-      )
-    }
+    // Emit the viewport (pan/zoom + once on first idle) for the POI-explore pill.
+    const emitViewport = () => reportGlViewport(map, onViewportChangeRef.current)
     map.on('moveend', emitViewport)
     map.once('idle', emitViewport)
     // Clear the hover card (and the anchored POI popup) as soon as the camera