fix(transactions): steer duplicate guard to matching for ledger-only vouchers (#958)

When the booking-time duplicate guard flags a ledger-only voucher
candidate (transaction_id null: a verifikat from an SIE import, a paid
invoice, a salary payout), the dialog's primary action is now "Matcha
mot verifikatet": it links the bank transaction to the existing voucher
via /api/reconciliation/bank/link (the same path MatchVoucherDialog
uses) instead of double-booking the same affarshandelse. "Bokfor anda"
stays available but demoted to an outline button. Sibling-transaction
candidates keep today's layout: matching a second bank line onto a
voucher that already has one is the N:1 edge case, not the default.

Wired through both call sites: the transactions page (runCategorize)
reuses handleVoucherLinked's refresh, and TransactionBookingDialog
(JournalEntryForm, /api/transactions/[id]/book path) reuses the booked
flow so in-dialog attached documents land on the matched verifikat and
the row leaves the list, with a "Bankhandelsen kopplad" toast instead
of "Bokford". No lib change: the candidate payload already carries the
transaction_id discriminator, covered by existing detection tests.

Closes #919.

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

messages/en.json

@@ -3872,6 +3872,8 @@
     "dialog_duplicate_voucher_label": "Voucher {label}",
     "dialog_duplicate_voucher_generic": "Existing voucher",
     "dialog_duplicate_view_voucher": "View the voucher",
+    "dialog_duplicate_match": "Match to the voucher",
+    "dialog_duplicate_match_failed": "Could not match",
     "dialog_duplicate_book_anyway": "Book anyway",
     "dialog_duplicate_cancel": "Cancel",
     "load_failed_title": "Could not load transactions",

messages/sv.json

@@ -3872,6 +3872,8 @@
     "dialog_duplicate_voucher_label": "Verifikat {label}",
     "dialog_duplicate_voucher_generic": "Befintlig verifikation",
     "dialog_duplicate_view_voucher": "Visa verifikatet",
+    "dialog_duplicate_match": "Matcha mot verifikatet",
+    "dialog_duplicate_match_failed": "Kunde inte matcha",
     "dialog_duplicate_book_anyway": "Bokför ändå",
     "dialog_duplicate_cancel": "Avbryt",
     "load_failed_title": "Kunde inte ladda transaktioner",