test(shared): type the cluster icon size check and tighten the comments

iconSize is a PointExpression, which has no x on its tuple form, so the client typecheck refused the size assertion; it now compares against L.point. The test ids follow the FE-PAGE-SHARED-MAP scheme in the order they run, and the comments around the cluster group say in a line what they said in a paragraph.

client/src/components/Map/markerCluster.ts

@@ -1,12 +1,8 @@
 import L from 'leaflet'
 
 /**
- * The cluster group every place map is drawn with.
- *
- * The planner and the public share page draw the same trip, so they have to
- * cluster it the same way: a shared link that opens on three dozen overlapping
- * pins while the planner shows four tidy bubbles is one trip told two different
- * ways. Both maps build their group from this block and this factory (#2343).
+ * The cluster group the planner and the public share page both draw places with,
+ * so a shared link clusters a trip the way the planner does (#2343).
  */
 export const CLUSTER_OPTIONS = {
   chunkedLoading: true,
@@ -26,13 +22,7 @@ export interface ClusterLike {
   getChildCount: () => number
 }
 
-/**
- * A count bubble, sized by what it stands for.
- *
- * Markup rather than a component because Leaflet owns this element:
- * `L.divIcon`'s html lands in the marker pane, outside React's tree — which is
- * also why its styling lives in index.css (`.marker-cluster-custom`).
- */
+/** A count bubble sized by its count, styled by `.marker-cluster-custom` in index.css. */
 export function createClusterIcon(cluster: ClusterLike) {
   const count = cluster.getChildCount()
   const size = count < 10 ? 36 : count < 50 ? 42 : 48

client/src/pages/SharedTripPage.test.tsx

@@ -24,10 +24,7 @@ vi.mock('react-leaflet', () => ({
   }),
 }));
 
-// The markers now reach the map through a cluster group (#2343). The real wrapper
-// asks React Leaflet's context for the map it belongs to, and the stubbed
-// MapContainer above provides none — so it is stubbed for the same reason
-// everything else here is.
+// The real cluster group needs the map context the stubbed MapContainer lacks (#2343).
 vi.mock('react-leaflet-cluster', () => ({
   default: ({ children }: { children?: React.ReactNode }) => (
     <div data-testid="marker-cluster-group">{children}</div>

client/src/pages/SharedTripPage.tsx

@@ -19,9 +19,7 @@ import { createElement, useEffect, useRef } from 'react';
 import { renderIconMarkup } from '../utils/iconMarkup';
 import { MapContainer, Marker, Polyline, TileLayer, Tooltip, useMap } from 'react-leaflet';
 import MarkerClusterGroup from 'react-leaflet-cluster';
-// leaflet.markercluster's own sheets travel with the planner's MapView, which this
-// page never mounts: without them the bubbles keep the library's default styling
-// and spiderfy's legs are invisible.
+// MapView brings these sheets for the planner, and this page never mounts it.
 import 'leaflet.markercluster/dist/MarkerCluster.css';
 import 'leaflet.markercluster/dist/MarkerCluster.Default.css';
 import { CLUSTER_OPTIONS, createClusterIcon } from '../components/Map/markerCluster';
@@ -461,10 +459,7 @@ export default function SharedTripPage() {
                     interactive={false}
                   />
                 )}
-                {/* Clustered like the planner's map (#2343). A shared link draws the
-                    whole trip at once on a 300px-tall map, where a stop a few blocks
-                    from the next one is the same few pixels: unclustered, the pins
-                    cover each other and the ones underneath cannot be tapped. */}
+                {/* Clustered like the planner's map, so nearby stops stay tappable (#2343). */}
                 <MarkerClusterGroup {...CLUSTER_OPTIONS} iconCreateFunction={createClusterIcon}>
                   {mapPlaces.map((p: any) => (
                     <Marker key={p.id} position={[p.lat, p.lng]} icon={createMarkerIcon(p, dayOrderMap[p.id] ?? null)}>