Add book title to autocomplete suggestions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/main.py

@@ -756,13 +756,14 @@ async def list_jobs(
 
 @app.get("/api/jobs/suggestions")
 async def job_suggestions():
-    """Return distinct values for author, chapter, and reviewer_name to power autocomplete."""
+    """Return distinct values for author, book, chapter, and reviewer_name to power autocomplete."""
     try:
         with get_db() as conn:
             with conn.cursor() as cur:
                 cur.execute("""
                     SELECT
                         array_remove(array_agg(DISTINCT author ORDER BY author), NULL) AS authors,
+                        array_remove(array_agg(DISTINCT book ORDER BY book), NULL) AS books,
                         array_remove(array_agg(DISTINCT chapter ORDER BY chapter), NULL) AS chapters,
                         array_remove(array_agg(DISTINCT reviewer_name ORDER BY reviewer_name), NULL) AS reviewers
                     FROM ocr_jobs
@@ -774,6 +775,7 @@ async def job_suggestions():
 
     return JSONResponse({
         "authors": row["authors"] or [],
+        "books": row["books"] or [],
         "chapters": row["chapters"] or [],
         "reviewers": row["reviewers"] or [],
     })