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

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

src/mapStackUnavailableReason.test.mjs

@@ -0,0 +1,20 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { MapStackController, photorealUnavailableReason } from './mapStackController.js';
+
+test('missing photoreal credentials explain both supported setup routes', () => {
+  assert.match(photorealUnavailableReason(false), /Needs GOOGLE_MAPS_API_KEY.*Provider Settings/);
+  assert.match(photorealUnavailableReason(false), /Cesium ion token/);
+});
+
+test('a configured but failed photoreal route does not ask for another key', () => {
+  const reason = photorealUnavailableReason(true);
+  assert.match(reason, /unavailable.*restrictions, quota, or network/);
+  assert.doesNotMatch(reason, /Needs|add it/);
+});
+
+test('controller credential detection accepts ion without a browser global', () => {
+  const hasCredentials = MapStackController.prototype._hasPhotorealCredentials;
+  assert.equal(hasCredentials.call({ cesiumToken: 'configured' }), true);
+  assert.equal(hasCredentials.call({ cesiumToken: '   ' }), false);
+});