Match Suggestion (no-write)

Run the patient matcher against caller-supplied identifiers and return the verdict. Never persists. The verdict's kind tells the caller how to render its picker: hard (lock — external-id / name+DOB uniqueness), medium (pre-fill with override — phone/email + name heuristic), soft (pre-fill, confirm — a single same-name patient with no date of birth to confirm), or none. Used by the file detail page to lock or pre-fill its patient picker, and by future eligibility / prior-auth extraction surfaces. Identifiers are normalized with the same forgiving parsers the upsert endpoint uses, so callers can pass raw values from extracted document data.