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

plan/served.md

@@ -1596,10 +1596,11 @@ Each unit follows the 8.0.4 template. "A-n" is an owner answer numbered in 8.3.1
    - The workpaper template is `crates/ledger-import/templates/workpaper.typ` with `crates/ledger-import/src/workpaper.rs` (that is where the other templates live), not `templates/workpaper.typ`. `audit.run` also carries `workpaper_pdf` (the JSON is `workpaper_attachment`). A run is idempotent on (through, figure head, scope, programme); `through_seq` is the figure head (the last line bearing on a figure: audits, attestations, evidence filings, decisions and the format declaration do not move it), not the journal head.
    - `policy.attestation_bar` is one canonical text, `effort=high verifiers=2 adversarial=true`, not an object (the TOML codec has no table value); `Kind::AttestationBar`. `counted` is read when asked; a month needs the effort, a year-level run (annual, cpa_handoff, full) the whole bar.
    - Scopes: `books.audit` previews at books:write and runs at books:post; the three attest tools are books:write; `books.workpaper` and `books.attestations` books:read. `books.attest_period` takes `period` as an id or a name. A receipt reading agrees when its amount is the entry's debit total or any one line, and its date the entry's.
-   - The CPA gate applies only on books that declared `audits`, so merging changes nothing on the live books before the go-ahead. `books.export_cpa_package` gained `without_audit_reason`.
-   - Needs attention: "Month-end attestation due", "Full audit due before the CPA handoff" and "Annual audit due", only for books that declared `audits`. The `audit` prompt (P5) was not written: P5 has not merged and `tools/prompts.rs` does not exist; the procedure is the handbook section `attestations-and-audit`.
+   - The CPA gate applies only on books that declared `audits`, so merging changes nothing on the live books before the go-ahead. `policy.cpa_package_requires_audit` unset means refuse once the books hold an audit run and warn before (not refuse from the start: every export of fresh books in ~30 existing tests would otherwise need a reason); the owner who wants it refused from the start sets `refuse`. `books.export_cpa_package` gained `without_audit_reason`.
+   - Needs attention: "Month-end attestation due", "Full audit due before the CPA handoff" and "Annual audit due", only for books that declared `audits`. The `audit` prompt (P5) gives the audit procedure; the attestation procedure is the handbook section `attestations-and-audit`.
    - `period.attested` was the placeholder "unknown event" in `tests/format.rs` and `ledger-gui/tests/newer_journal.rs`; they use `ledger.not_yet_written` now.
    - 8.0.6: `books_written_under_older_rules_still_open` hand-writes the four events; fixture `old-books/p8_before` (writer `p8_before.rs`, run against b97234ac); `audits_is_its_own_feature`; `books_p2_served_cut_over_whole` refuses `books.audit` and `books.review_entry` before consent. No figure moved, no golden changed. Merge does not need the owner's go-ahead; the live books refuse the new writes until he gives it.
+   - Fitted to P5 after it merged first: `next_steps.rs` (after `books.close_period` the steps are `books.audit` and `books.attest_period`; an audit's run leads to `books.workpaper`, the receipt and entry attestations and `books.attest_period`; the attest tools lead to `books.attestations` and `books.export_cpa_package`), the guard `audit_required` (remedy `books.audit`, also the refusal of a stale `books.attest_period`), the `audit` prompt names the audit tools, and the tool count is 140.
    - No kernel, Kani or Lean change.
 
 **Struck from P8:** ~~bar versioning (`counts` derived against the bar in force at that seq; `bar_change_is_prospective`), the Lean counting lemma~~ → IZ-3d; ~~"vault public-key sha"~~ → D-48; ~~"access-log tooling"~~ → `books.access_log` exists (P2); ~~`books.audit` run as a job~~ → D-53.