test(store): S4.2's shapes open old books and wait for consent (P4b S4.2)

The 8.0.6 checklist for this slice, which adds fields on party.updated
(an email and two default terms) and the invoicing settings it guards:

1. books_written_under_older_rules_still_open now hand-writes a party's
   email and terms and an invoicing setting through JournalWriter, and the
   books still open, verify and replay them.
2. A new old-books fixture, p4_s42_settings_parties, was written by the
   version before this slice (1bfce915, through the old-books-writer
   harness) with a party, a vendor, two posted entries and three settings,
   and its expected.json from that version's code. This version opens it,
   verifies it and reports its figures identically.
3. books_p2_served_cut_over_whole gains a refused invoicing setting before
   the go-ahead; the same call succeeds after it.
4. documents_v2_is_its_own_feature: books that declared every earlier
   feature stop at its declaration as newer, wait for the upgrade, and
   name exactly it in the upgrade.
No figure moves (item 5): settings and party facts enter no report.

Merge does not need the owner's go-ahead; the live books refuse the new
party and setting writes with the upgrade remedy until he gives it.

crates/ledger-cli/tests/format_upgrade.rs

@@ -722,6 +722,13 @@ fn books_p2_served_cut_over_whole() {
             json!({"decided_by": "Avery Quill",
                    "changes": [{"key": "books.schedule_convention", "value": "monthly_even"}]}),
         ),
+        // An invoicing setting (documents_v2, P4b S4.2): an older version
+        // refuses the key.
+        (
+            "books.set_setting",
+            json!({"decided_by": "Avery Quill",
+                   "changes": [{"key": "invoicing.default_terms", "value": "Net 30"}]}),
+        ),
         (
             "books.add_account",
             json!({"code": "4900", "name": "Gain on sale", "account_type": "revenue",