fix(api-v1): propagate underlag when booking via v1 categorize routes (#1564)

The v1 categorize and batch-categorize routes create the journal entry
via createTransactionJournalEntry directly and never ran the shared
underlag propagation, so a booking made through the API-key surface
left the transaction's pinned document unanchored and matched inbox
items unstamped: the same "Underlag saknas" gap #1560 closed for the
dashboard, /book and bulk-book paths, surviving on this one surface.

Both routes now call propagateUnderlagForBookedTransaction after the
CAS write succeeds (only when this request owns the booking; skipped on
partial success and lost CAS races). Best-effort by contract, same as
every other caller: a propagation failure is logged inside the helper
and never fails the booking.

Also adds the attach-after-bulk-book unit test salvaged from the closed
duplicate PR #1559: a document pinned to a bulk-booked transaction
(verifikat anchored via transaction_voucher_links) is anchored against
the samlingsverifikat when attached after the booking.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

lib/transactions/__tests__/inbox-underlag.test.ts

@@ -333,4 +333,26 @@ describe('completeInboxItemsForBookedTransaction', () => {
       { created_journal_entry_id: JE2 },
     ])
   })
+
+  it('anchors a pinned document against the samlingsverifikat on attach-after-bulk-book', async () => {
+    // A bulk-booked tx keeps transactions.journal_entry_id null: its verifikat
+    // hangs off transaction_voucher_links. A document attached AFTER that
+    // booking (with no inbox item) must still land on the samlingsverifikat:
+    // voucher-link resolution feeds the pin leg of the propagation.
+    const { supabase, enqueue, findCalls } = createQueuedMockSupabase()
+    enqueue({ data: [{ transaction_id: TX1, journal_entry_id: JE2 }] }) // voucher links
+    enqueue({ data: { document_id: 'doc-pin' } }) // tx pin lookup
+    enqueue({ data: { journal_entry_id: null } }) // pinned doc unanchored
+    enqueue({ data: [] }) // no matched inbox items
+
+    const result = await completeInboxItemsForBookedTransaction(
+      supabase as unknown as SupabaseClient,
+      COMPANY,
+      TX1,
+      { directJournalEntryId: null },
+    )
+    expect(result).toBe(JE2)
+    expect(linkToJournalEntry).toHaveBeenCalledWith(expect.anything(), COMPANY, 'doc-pin', JE2)
+    expect(findCalls('invoice_inbox_items', 'update')).toEqual([])
+  })
 })