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>

DECISIONS.md

@@ -51,3 +51,4 @@ One line per decision: `[YYYY-MM-DD] <decision>: <why>`. Appended by agents and
 [2026-07-08] Pinned @anthropic-ai/bedrock-sdk to exact 0.29.1 (dependabot #884 auto-bumped it to 0.32.0, which broke Bedrock streaming in prod: empty stream / "request ended without sending any chunks"). Guarded three ways against accidental re-bump: exact pin in package.json, dependabot ignore, and a pinned-dep check in scripts/checks/no-new-antipatterns.mjs (check:guards). Unpin only once 0.32.x streaming is verified against Bedrock.
 [2026-07-09] Issue #916 (disconnect orphans ledger accounts): release claims by demoting cash_accounts rows to manual (bank_connection_id = null), never deleting: transactions.cash_account_id and ledger history reference the rows, and upsertFromPsd2 promotes a manual holder in place on reconnect so the bank lands back on its original BAS slot. Orphans predating the fix self-heal via a revoked-status filter in the allocator + collision guard (not data repair). When a promote collides with a duplicate row for the same connection+uid (callback mirrored onto an overflow slot pre-fix), the duplicate is deleted only if it has zero linked transactions, otherwise demoted: preserves FK links while freeing the slot. Picker-save rejections now render inline in the picker instead of routing to the sync-progress modal, whose parent-unmount-on-close made every save outcome invisible.
 [2026-07-09] #917 fix scoped to the current-year suggestion: "Sedan räkenskapsårets början" now resolves from the fiscal_periods row containing today, but the "Föregående räkenskapsårets start" custom option still derives from the recurring fiscal_year_start_month: the issue only covers the current-year date and a first-year company has no previous period row to resolve against.
+[2026-07-09] Issue #919 (duplicate guard should steer to matching): the match action lives INSIDE DuplicateBookingDialog (fetch to /api/reconciliation/bank/link + account resolution via /api/cash-accounts + resolveAccount, exactly the MatchVoucherDialog path) rather than in each call site or a new endpoint: both call sites (transactions page runCategorize + TransactionBookingDialog/JournalEntryForm) share one implementation and pass only the transaction context + an onMatched callback mirroring onLinked. Match is primary ONLY for ledger-only candidates (transaction_id null, the SIE-import case); sibling-transaction candidates keep "Bokför ändå" primary since N:1 matching is the edge case. No lib change: the candidate already carries the transaction_id discriminator, covered by existing tests.