merge: P4b S5, sent tracking (branch S5, ad649be3)

The second of the paused branches. invoice.sent, Ledger::mark_sent (with
its Lean step), books.mark_sent in its own group, the two attention
items, schema 17. Conflicts, resolved as plan 8.0.2 says: the shared
over-the-wire test file crates/ledger-cli/tests/documents.rs (S4.4's
file kept whole, S5's test appended, its create call given the
confirmed: true the S4.4 contract now needs), types.rs (both appends
kept), docs/parity.md (the review's oracle row and S5's new row).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

crates/ledger-cli/tests/format_upgrade.rs

@@ -760,6 +760,16 @@ fn books_p2_served_cut_over_whole() {
     // A project by name alone is a plain class, which P2 reads.
     a.call("books.add_project", json!({"name": "Lighthouse"}))
         .unwrap();
+    // An invoice for the send below: a document P2 reads (no new fields),
+    // so it is written before the go-ahead; its send waits for it.
+    let invoice = a
+        .call(
+            "books.create_invoice",
+            json!({"party_id": 1, "date": "2026-01-05", "due_date": "2026-02-04",
+                   "lines": [{"description": "Design", "amount": "400.00"}], "confirmed": true}),
+        )
+        .unwrap()["id"]
+        .clone();
     let waiting = journal(&dir);
     let refused: Vec<(&str, Value)> = vec![
         // An invoice carrying documents_v2's fields (terms: P4b S4.4) and
@@ -793,6 +803,13 @@ fn books_p2_served_cut_over_whole() {
             json!({"decided_by": "Avery Quill",
                    "changes": [{"key": "invoicing.default_terms", "value": "Net 30"}]}),
         ),
+        // A recorded send (invoice.sent, documents_v2, P4b S5): an older
+        // version refuses the type.
+        (
+            "books.mark_sent",
+            json!({"invoice": invoice.to_string(), "on": "2026-01-06",
+                   "by": "Avery Quill", "recipients": ["billing@fernhill.example"]}),
+        ),
         (
             "books.add_account",
             json!({"code": "4900", "name": "Gain on sale", "account_type": "revenue",