5e9aa52dea
Links an uploaded document directly to a posted verifikation (journal entry) via the staged-operation pattern. Covers imported/manual vouchers that have no bank-transaction row — the gap left by gnubok_attach_document_to_transaction. - New MCP tool gnubok_link_document_to_voucher (bookkeeping:write scope) - New pending-operation type link_document_to_voucher (medium risk) - Commit executor with WORM guard: refuses to re-link a doc already pinned to a different posted JE (BFL 5 kap 6 §); allows overwriting a draft-JE link; maps period-lock throws to 409 - 5 executor unit tests covering 404, WORM 409, draft-allow, happy path, and period-lock Signed-off-by: Jonas Flodén <jonas@floden.nu>