Maps · View: a focused pin keeps focus off view

Each pin holds a keyed focus handle of its own, a Tab stop and pressable
while its place is in view, so a focused pin that pans out of view keeps
focus and the arrows go on panning, and a popup that scrolls away hands
focus back to its pin wherever it lies. A popup whose place is off view
takes no focus. Tests hold the tall card's cap and scrolling body, the
map staying under its wheel, and markers refuse a repeated key.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tasks/ch31-43.md

@@ -291,7 +291,7 @@
 ## T41a Maps · View — `src/maps`
 
 - [x] MapView — host tiles → `maps::MapView`: the host's tile for each zoom, column and row, the nearest cut scaled past its zooms; a drag, the wheel or the arrows pan, Command-wheel, + and - or its buttons zoom
-- [x] MapMarker → `maps::MapMarker`, a pin keyed by its place's name, pressable while in view when the map hears it
+- [x] MapMarker → `maps::MapMarker`, a pin keyed by its place's name, a Tab stop and pressable while in view when the map hears it; a focused pin keeps focus as it leaves the view
 - [x] MapPopup → `maps::MapPopup`, over or under its point toward the larger half, held inside the map, its body scrolling past the room; it takes focus when it shows and hands it back when it goes
 - [x] LocationPicker → `maps::LocationPicker`, the place under a center crosshair
 - [x] CoordinateDisplay → `maps::CoordinateDisplay`, degrees or degrees, minutes and seconds, copyable