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

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

src/data/installationFeedback.test.mjs

@@ -0,0 +1,21 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { installationFeedback } from './installationFeedback.js';
+
+test('retry copy follows the real deadline and does not promise an overdue timer fired', () => {
+  assert.equal(installationFeedback({ retryAt: 31000 }, 1000), 'Overpass temporarily unavailable — retrying in 30s');
+  assert.match(installationFeedback({ retryAt: 31000 }, 32000), /retry pending$/);
+  assert.match(installationFeedback({ retryAt: 241000 }, 1000), /240s$/);
+});
+test('only known failure reasons get specific attribution', () => {
+  for (const [failureReason, text] of [['rate_limited', 'rate-limited'], ['timeout', 'timed out'], ['query_failed', 'could not complete']]) {
+    assert.ok(installationFeedback({ status: 'unavailable', failureReason }).includes(text));
+  }
+  assert.match(installationFeedback({ status: 'unavailable', failureReason: 'unknown' }), /temporarily unavailable/);
+});
+test('first fetch, retry, cached data and success have distinct copy', () => {
+  assert.equal(installationFeedback({ loading: true }), 'Fetching mapped sites…');
+  assert.equal(installationFeedback({ loading: true, retrying: true }), 'Retrying mapped sites…');
+  assert.equal(installationFeedback({ status: 'ready' }), 'Mapped sites loaded');
+  assert.equal(installationFeedback({ stale: true }), 'Showing cached mapped sites');
+});