Teaching tools: word occurrences, blanks handout, templates, series progress, book info, comments

- Words tab: "Where else" lists every verse using a Strong's number, by book
  (new /api/strongs/:number/occurrences, indexed from the interlinear files)
- Handout: fill-in-the-blanks layout with a word bank
- Four new study templates: character, topical, word, verse by verse
- Finish: series progress (not started / studied / ready / taught)
- Background: book at a glance for all 66 books
- Chunk comments for co-teachers, merged between copies
- TODO: correct BSB audio note, tick co-teacher comments

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

src/syncService.js

@@ -318,4 +318,8 @@ export async function adminGetProject(id) {
 
 export async function adminDeleteProject(id) {
   return request('DELETE', `/admin/projects/${id}`);
-}
+}
+// Every verse that uses a Strong's number, grouped by book: { strongs, total, books: [{ book, name, count, refs }] }
+export async function getStrongsOccurrences(strongs) {
+  return request('GET', `/strongs/${encodeURIComponent(strongs)}/occurrences`);
+}