Add Insights, Observe-first, compare, handout layouts, richer search, backup nudge

- Commentary and study aids wait for 15 words of your own Observe notes.
- Insights page: this week's own work, themes across studies, words you keep
  studying, what slipped in recalls, open follow-ups.
- Recall can record what slipped; session notes (teach it back, who came,
  group notes, follow-ups); "Pray about this" from Apply.
- Compare any two passages side by side.
- Handout layouts: standard, questions only, large print, note-taking.
- Search understands "in <book>", "last week/month/year" and a year.
- Home shows the last backup age and nudges after two weeks.
- Phone: the stage bar scrolls instead of clipping Script and Export.

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

src/utils/backup.js

@@ -89,3 +89,14 @@ export function mergeReadingPlans(local, incoming) {
     activity: [...new Set([...(local.activity ?? []), ...(incoming.activity ?? [])])].sort(),
   };
 }
+
+// When you last downloaded a backup on this device, so Home can say so (and nudge when it has been a while).
+const LAST_BACKUP_KEY = 'last-backup-at';
+export const markBackedUp = (now = Date.now()) => { try { localStorage.setItem(LAST_BACKUP_KEY, String(now)); } catch { /* storage unavailable */ } };
+export const lastBackupAt = () => { try { return Number(localStorage.getItem(LAST_BACKUP_KEY)) || null; } catch { return null; } };
+export function backupAge(at, now = Date.now()) {
+  if (!at) return { text: 'You haven’t downloaded a backup yet', stale: true };
+  const days = Math.floor((now - at) / 86400000);
+  if (days < 1) return { text: 'Backed up today', stale: false };
+  return { text: `Last backup ${days} day${days === 1 ? '' : 's'} ago`, stale: days >= 14 };
+}