deps: react-leaflet 1.8 -> 4.2 (+ leaflet 1.9) — the last legacy react-* lib

Ground-up hooks rewrite of the app's core map. Removes the final batch of
React-19-blocking warnings (legacy context on Map/LayersControl/TileLayer/
Marker/CircleMarker/Circle/Tooltip + ReactDOM.render from the old controls).

Core: <Map> -> <MapContainer>; .leafletElement refs (6 files) -> the map/
layer instances directly, via a <MapReady> child (useMap) + plain refs on
Marker/Circle/GeoJSON; controlled viewport (onViewportChanged + state.center/
zoom) -> <MapEvents> (useMapEvents moveend/zoomend) + imperative setView;
onClick -> eventHandlers={{click}}; Path styling -> pathOptions/style;
subsUnion takes the L.Map directly.

The 4 v1-only plugins reimplemented (new in-repo helpers under Maps/):
- react-leaflet-control -> MapControl (L.Control + createPortal)
- react-leaflet-google  -> GoogleMutantLayer (createLayerComponent +
  leaflet.gridlayer.googlemutant; Google Maps API already loaded by Gkeys)
- react-leaflet-fullscreen -> createControlComponent + leaflet.fullscreen
- leaflet-sleep / leaflet-graphicscale kept as vanilla (work on leaflet 1.9)

Browser-verified: /fires (tiles, OSM+Google layer switch, custom control,
fullscreen, graphic scale, pan/zoom -> re-fetch, no NaN), fire detail
(GeoJSON rect + fitBounds), home (3 maps coexist; SelectionMap draggable
marker -> updatePosition + distance circle). Console now shows 0 React
warnings on home/fires. REST smoke byte-identical.

imports/ui/components/Maps/DefMapLayers.js

@@ -5,7 +5,7 @@
 import React, { Component } from 'react';
 import PropTypes from 'prop-types';
 import { withTranslation } from 'react-i18next';
-import { GoogleLayer } from 'react-leaflet-google/lib/';
+import GoogleMutantLayer from '/imports/ui/components/Maps/GoogleMutantLayer';
 import Gkeys from '/imports/startup/client/Gkeys';
 import { TileLayer, LayersControl } from 'react-leaflet';
 
@@ -54,15 +54,15 @@ class DefMapLayers extends Component {
         {/* React.Fragment does not work here */}
         { this.state.gkey &&
         <BaseLayer name={t('Mapa de carreteras de Google')}>
-          <GoogleLayer opacity={defOpacity} googlekey={this.state.gkey} maptype="ROADMAP" />
+          <GoogleMutantLayer opacity={defOpacity} maptype="ROADMAP" />
         </BaseLayer> }
         { this.state.gkey &&
           <BaseLayer name={t('Mapa de terreno de Google')} checked={this.props.terrain}>
-            <GoogleLayer opacity={defOpacity} googlekey={this.state.gkey} maptype="TERRAIN" />
+            <GoogleMutantLayer opacity={defOpacity} maptype="TERRAIN" />
           </BaseLayer> }
         { this.state.gkey &&
           <BaseLayer name={t('Mapa de satélite de Google')} checked={this.props.satellite}>
-            <GoogleLayer opacity={defOpacity} googlekey={this.state.gkey} maptype="SATELLITE" />
+            <GoogleMutantLayer opacity={defOpacity} maptype="SATELLITE" />
           </BaseLayer> }
       </LayersControl>
     );