Super-admin auto-apply of high-confidence engine document-match proposals

Super-admin Stage-1 sweep. Promotes high-precision engine document↔transaction match proposals (method exact_amount_date_vendor, confidence >= minConfidence, expense document -> outflow transaction, single unambiguous candidate, and current amount/date/vendor evidence still matching) to applied matches, reusing the standard match path so GL side-effects and reconciliation guards are inherited. Defaults to a dry-run; pass dryRun=false to write.