Run download jobs and deliver books to CWA

Jobs download new chapters, recheck chapters, replace the book, update
metadata or rebuild from stored chapters. Locked metadata fields keep
their values. A scheduler queues updates. An update finds the library
book of a story through CWA, and fails with an error if it cannot, so
that it never makes a duplicate book.

tests/test_backup.py

@@ -0,0 +1,25 @@
+"""Daily backups of the database and personal.ini."""
+
+import sqlite3
+from datetime import date
+
+from bindery.backup import daily_backup
+from bindery.store import Store
+
+
+def test_one_backup_a_day_and_only_the_newest_are_kept(tmp_path):
+    store = Store(tmp_path / "bindery.db")
+    store.create_story("https://example.com/s/1", "example.com", "T", "A", [])
+    ini = tmp_path / "personal.ini"
+    ini.write_text("[defaults]\n")
+    folder = tmp_path / "backups"
+    for day in range(1, 11):
+        daily_backup(store, folder, ini, 7, date(2026, 9, day))
+    assert daily_backup(store, folder, ini, 7, date(2026, 9, 10)) is None
+    names = sorted(p.name for p in folder.iterdir())
+    assert names == [f"bindery-2026-09-{d:02}.db" for d in range(4, 11)] + [
+        f"personal-2026-09-{d:02}.ini" for d in range(4, 11)
+    ]
+    copy = sqlite3.connect(folder / "bindery-2026-09-10.db")
+    assert copy.execute("SELECT title FROM stories").fetchall() == [("T",)]
+    copy.close()