feat(bookkeeping): agent attribution into the immutable ledger layer (P0-1) (#678)

* feat(bookkeeping): agent attribution into the immutable ledger layer

Close the three attribution gaps left after 20260618120001 (which made
commit_method record 'api_key' for MCP-relayed approvals):

- journal_entries gains nullable committed_actor_type/committed_actor_label,
  stamped by commit_journal_entry in the same draft->posted UPDATE that
  writes commit_method. The RPC gains p_actor_type/p_actor_label
  (DEFAULT NULL; prior signature dropped first to avoid PostgREST overload
  ambiguity, same technique as 20260421140000).
- write_audit_log now populates audit_log.actor_type/actor_label from
  transaction-local gnubok.actor_* GUCs set by the RPC (the established
  gnubok.allow_delete pattern). Unset GUCs COALESCE to 'user' — byte-
  identical to the column's previous effective DEFAULT for every
  pre-existing write path.
- commitPendingOperation accepts opts.actor and runs the entire executor
  inside an AsyncLocalStorage runWithActor() scope read by commitEntry(),
  so EVERY journal commit an operation makes is attributed — closing the
  documented "commitMethod only reaches create_voucher" gap. MCP approve
  passes the api_key actor + key label; web single/bulk approve pass the
  user + email.

Known limitation (documented): reverseEntry posts reversal vouchers via
direct PostgREST writes, not the commit RPC — reversals keep NULL
attribution until that path is RPC-ified (follow-up).

pg-real coverage: lib/bookkeeping/__tests__/commit-actor.pg.test.ts
(RPC param stamping, audit GUC read, transaction-locality, CHECK
rejection, immutability of the new columns, single-signature guard).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* fix(bookkeeping): split actor-context so client bundles never see node:async_hooks

CI core-only build failed: engine.ts is reachable from client component
bundles (invoices/[id] page), and the static node:async_hooks import in
actor-context.ts cannot be chunked for the browser. Split the module:

- actor-context.ts (isomorphic): CommitActor type + a storage registry +
  getActor(). In a client bundle the registry stays empty and getActor()
  returns undefined — identical to the server-side no-scope default.
- actor-context-node.ts (server-only): owns the AsyncLocalStorage, binds it
  into the registry on import, exports runWithActor(). Imported only by the
  approval paths (commit.ts), which are never client-reachable.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/bookkeeping/engine.ts

@@ -13,6 +13,7 @@ import {
 } from '@/lib/bookkeeping/errors'
 import { resolveDefaultSeriesForSource } from '@/lib/bookkeeping/voucher-series-resolver'
 import { syncInvoiceStatusFromPaymentEntry, isPaymentSourceType } from '@/lib/bookkeeping/payment-sync'
+import { getActor } from '@/lib/bookkeeping/actor-context'
 import type {
   CreateJournalEntryInput,
   CreateJournalEntryLineInput,
@@ -342,6 +343,12 @@ export async function createDraftEntry(
  * Uses the atomic commit_journal_entry RPC so the voucher number increment
  * and status update happen in one transaction. If the balance trigger rejects
  * the entry, the sequence increment rolls back — no burned numbers.
+ *
+ * Actor attribution: the surrounding runWithActor() scope (set by the
+ * approval entry points — commitPendingOperation, web approve routes) is
+ * forwarded to the RPC, which stamps journal_entries.committed_actor_* and
+ * the audit_log COMMIT row (migration 20260619120000). No scope → NULLs,
+ * identical to pre-attribution behaviour.
  */
 export async function commitEntry(
   supabase: SupabaseClient,
@@ -351,6 +358,7 @@ export async function commitEntry(
   commitMethod?: string,
   rubricVersion?: string
 ): Promise<JournalEntry> {
+  const actor = getActor()
 
   // Atomic: increment voucher sequence + update status in one transaction.
   // Rolls back the sequence if the balance trigger or any constraint fails.
@@ -359,6 +367,8 @@ export async function commitEntry(
     p_entry_id: entryId,
     p_commit_method: commitMethod ?? null,
     p_rubric_version: rubricVersion ?? null,
+    p_actor_type: actor?.type ?? null,
+    p_actor_label: actor?.label ?? null,
   })
 
   if (commitError) {