feat(audit): books.audit, the attestation tools and the CPA gate (P8)

The whole re-audit through the tools: books.audit previews its checks, then
with the preview's digest runs them, files the workpaper and journals the
run; the same books, day and scope return the run that exists.
books.attest_receipt, books.review_entry and books.attest_period record a
named client's claim with its self-reported method; books.attestations
weighs each against policy.attestation_bar as it stands. Under
policy.cpa_package_requires_audit = refuse, books that declared audits
cannot export the CPA package without a counted audit for the handoff at the
current head unless a reason is given, which is journaled as a decision
(D-9). Needs attention asks for the month-end attestation, the annual audit
and the audit before the handoff. Rules B-45, the handbook section, the
interface, parity, receipt-store and testing records, and the As-built
block. Merge needs no go-ahead: the live books refuse the new writes until
the owner gives it.

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

@@ -909,6 +909,16 @@ fn books_p2_served_cut_over_whole() {
             json!({"attachment_id": 1, "fields": {"payee": "Harbor Design LLC",
                    "amount": "12.34", "date": "2026-02-01"}}),
         ),
+        // An audit run and an attestation (audits, P8): an older version
+        // doesn't know the events.
+        (
+            "books.audit",
+            json!({"scope": "full", "through": "2026-02-28", "confirmed": true}),
+        ),
+        (
+            "books.review_entry",
+            json!({"entry_id": 1, "method": {"reasoning_effort": "high"}}),
+        ),
     ];
     for (tool, args) in &refused {
         let e = a.call(tool, args.clone()).unwrap_err();