fix(map): keep the selected place findable on the map

Selecting a place no longer spiderfies a city-sized cluster: the reveal
only fans open bubbles of up to 12 stops, or stacks whose stops all share
one coordinate, so a zoomed-out trip with hundreds of places stays usable
(#2990).

The selected pin now carries a white border inside a pulsing blue ring on
both renderers (static under reduced motion), and the map measures the
place card instead of assuming a fixed 320px, so the selection pans the
pin above even a tall card on portrait tablets and eases it back out when
the card grows over it later (#2991).

Closes #2990
Closes #2991

client/src/components/Map/mapChromePadding.ts

@@ -0,0 +1,47 @@
+import type { ViewportPadding } from '../../utils/mapViewport';
+
+/** How far above the map's bottom edge the place card floats (PlaceInspector's `bottom`). */
+export const PLACE_CARD_OFFSET_PX = 20;
+/** Map kept clear above the place card, so a pin panned there is not touching its edge. */
+const PLACE_CARD_CLEARANCE_PX = 40;
+/** What a place card is assumed to cover before it has been measured. */
+const PLACE_CARD_MIN_COVER_PX = 320;
+
+export interface BottomChrome {
+  hasInspector?: boolean;
+  /** The place card's measured height in pixels, 0 or absent while it is not on screen. */
+  inspectorHeight?: number;
+  hasDayDetail?: boolean;
+}
+
+/**
+ * How much of the map's bottom edge the floating panels cover, the same on both renderers.
+ *
+ * The place card grows with its content up to 60vh, which on a portrait tablet reaches past
+ * the middle of the map. A fixed allowance put the selected pin right under it (#2991), so
+ * the card's real height counts once it is known; the fixed value stays the floor for the
+ * moment between the selection and the card's first layout.
+ */
+export function bottomChromePadding({ hasInspector, inspectorHeight = 0, hasDayDetail }: BottomChrome): number {
+  if (hasInspector)
+    return Math.max(PLACE_CARD_MIN_COVER_PX, inspectorHeight + PLACE_CARD_OFFSET_PX + PLACE_CARD_CLEARANCE_PX);
+  return hasDayDetail ? 280 : 60;
+}
+
+/**
+ * Whether a point on the map's container sits under the panels around it rather than in
+ * the open part of the map. Used to bring the selected pin back out after a panel grew
+ * over it, and to leave the camera alone when it did not.
+ */
+export function isUnderChrome(
+  point: { x: number; y: number },
+  size: { x: number; y: number },
+  padding: ViewportPadding
+): boolean {
+  return (
+    point.x < padding.left ||
+    point.x > size.x - padding.right ||
+    point.y < padding.top ||
+    point.y > size.y - padding.bottom
+  );
+}