App quality: offline badge, per-note history, keyboard study mode, notes import

- Study cards say whether the Bible text works offline, with a button to save
  the missing book (notes are always kept on the device).
- Each note keeps its last 12 versions with Restore (History under each note).
- Keyboard-only study: 1/2/3 write in Observe/Interpret/Apply, C/W/X/P switch
  resource tabs, V compares, Esc leaves a note box; listed under "?".
- Export > Import notes: bring Word/Markdown/text notes into the matching
  chunks without overwriting anything; can mark them as not your own.

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

src/utils/noteHistory.js

@@ -0,0 +1,23 @@
+// Earlier versions of a single note (Observe, Interpret, Apply…), kept on this device so one note can be rolled
+// back without restoring the whole study. A version is saved when you start and when you stop editing a note, so
+// whatever was there before a big rewrite is always a click away.
+export const MAX_VERSIONS = 12;
+const keyFor = (chunkId, field) => `note-history:${chunkId}:${field}`;
+
+// -> [{ at, text }], newest first
+export function listNoteVersions(chunkId, field) {
+  try {
+    const raw = JSON.parse(localStorage.getItem(keyFor(chunkId, field)) || '[]');
+    return Array.isArray(raw) ? raw.filter((v) => v && typeof v.text === 'string') : [];
+  } catch { return []; }
+}
+
+// Keeps `text` as the newest version unless it is blank or the same as the newest one. Returns the list.
+export function recordNoteVersion(chunkId, field, text, now = Date.now()) {
+  const list = listNoteVersions(chunkId, field);
+  const value = text ?? '';
+  if (!value.trim() || list[0]?.text === value) return list;
+  const next = [{ at: now, text: value }, ...list].slice(0, MAX_VERSIONS);
+  try { localStorage.setItem(keyFor(chunkId, field), JSON.stringify(next)); } catch { /* storage full or unavailable */ }
+  return next;
+}