feat(audit): fit the audit tools into the agent surface (P8)

After P5 merged first: a close leads to the audit and the period's
attestation, an audit run to its workpaper and the claims behind it, the
attest tools to the attestations and the CPA package; a refusal for want of
a standing audit is the guard audit_required with books.audit as its
remedy; the audit prompt runs the audit tools. policy.cpa_package_requires_audit,
unset, refuses once the books hold an audit run and warns before, so a
book that has not begun the programme is not stopped from its first handoff
by a rule it has not met; set to refuse, it holds from the start.
bookspec states B-45 (convention) in its checker.

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

crates/ledger-cli/tests/audit.rs

@@ -290,6 +290,14 @@ fn a_period_is_attested_on_a_standing_audit() {
 #[test]
 fn cpa_package_refuses_without_a_counted_audit_unless_a_reason_is_given() {
     let (_books, mut w, paper, rid, bare) = setup("p8-cpa");
+    // Unset, the package warns until the books hold an audit run; the
+    // owner who wants it refused from the start says so.
+    answer_of(&w.call(
+        "books.set_setting",
+        json!({"decided_by": "Avery Quill",
+               "changes": [{"key": "policy.cpa_package_requires_audit", "value": "refuse"}]}),
+    ))
+    .unwrap();
     let export = |w: &mut common::Wire, extra: Value| {
         let mut args = json!({"as_of": "2026-03-31", "cash_accounts": ["1000"],
                               "include_receipts": false, "include_tins": false});