fix: improve mapped installations and map-source guidance (#183)

Improve mapped installation recovery, deselection, retry feedback, and visual-style and map-source guidance.

src/mapStackChips.js

@@ -10,6 +10,8 @@
 // state is re-synced from controller state (never optimistically), so a failed
 // or superseded switch still leaves the truly-active stack lit.
 
+import { keySetupRequirement } from './keySetupCore.mjs';
+
 export const MAP_STACK_CHIP_CLASS = 'map-stack-chip';
 export const PRESENTED_MAP_STACK_IDS = Object.freeze([
   'photoreal',
@@ -36,7 +38,7 @@ export function mapStackChipModel(stack, activeId) {
   const label = String(stack?.label ?? stack?.id ?? '');
   const requiresIon = stack?.requiresIon === true;
   const fallbackReason = requiresIon
-    ? 'Cesium ion token required'
+    ? keySetupRequirement('cesium-ion')
     : `${label || 'This map stack'} is unavailable`;
   const unavailableHint = available ? '' : String(stack?.unavailableReason || fallbackReason);
   return {