docs(places): say where the map's places filter departs from the lists

The header claimed the lists and the map always agree. They apply the same
predicate to the same values, but the map narrows "planned" to the open day
(#2024) and leaves collapsed days' stops off.

client/src/mobile/screens/trip/places/placesBrowserModel.ts

@@ -12,8 +12,9 @@ import {
  * Pure filter model of the mobile places browser. Mirrors the desktop
  * sidebar's semantics exactly (usePlacesSidebar + the map's mapPlaces memo):
  * the pool filter, the category set and the rating floor come from the trip
- * store and go through the same matcher (utils/placesFilter), so the list here
- * and the map markers always agree (#1541).
+ * store and go through the same matcher (utils/placesFilter) as the map markers
+ * (#1541); the map's own exceptions (open day, collapsed days) are described
+ * there.
  */
 
 /** Kept under this name for the browser's callers; the predicate itself lives in utils/placesFilter. */

client/src/utils/placesFilter.ts

@@ -3,9 +3,11 @@ import type { Place } from '../types'
 /**
  * The trip's places filter, in one place: the pool (all / unplanned / planned /
  * tracks), the category set and the minimum rating. The desktop list, the phone
- * list and the map markers of both shells all filter through these helpers, on
- * the values held in the trip store, so the list and the map can never disagree
- * on which places are in view (#1541).
+ * list and the map markers of both shells apply this same predicate to the same
+ * values, held in the trip store (#1541). The map keeps two deliberate
+ * differences of its own: with a day open, "planned" shows that day's plan only
+ * (#2024), and the stops of collapsed days are left off the map (except under
+ * "planned").
  */
 
 /** A minimum of average stars: 'all', or a floor that unrated places fall through. */