settings: Records import & export for temetro data

Backend: GET /api/settings/records/export downloads the clinic's full patient
archive as JSON; POST /api/settings/records/import creates new patients (skips
existing file numbers, drops cross-clinic provider links). Both admin-gated.

Frontend: Records settings now has a working Export button and an Import flow
(choose file -> preview count -> apply) wired to the new endpoints.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/lib/records.ts

@@ -0,0 +1,46 @@
+import { apiFetch } from "@/lib/api-client";
+import type { Patient } from "@/lib/patients";
+
+// Shape of a temetro records archive (GET /api/settings/records/export).
+export type RecordsExport = {
+  temetroExport: true;
+  version: number;
+  exportedAt: string;
+  organizationId: string;
+  patientCount: number;
+  patients: Patient[];
+};
+
+// Summary returned by POST /api/settings/records/import.
+export type ImportResult = {
+  created: number;
+  skipped: number;
+  total: number;
+  errors: string[];
+};
+
+export function exportRecords(): Promise<RecordsExport> {
+  return apiFetch<RecordsExport>("/api/settings/records/export");
+}
+
+export function importRecords(patients: unknown[]): Promise<ImportResult> {
+  return apiFetch<ImportResult>("/api/settings/records/import", {
+    method: "POST",
+    body: JSON.stringify({ patients }),
+  });
+}
+
+// Trigger a browser download of a JSON archive.
+export function downloadJson(data: unknown, filename: string): void {
+  const blob = new Blob([JSON.stringify(data, null, 2)], {
+    type: "application/json",
+  });
+  const url = URL.createObjectURL(blob);
+  const a = document.createElement("a");
+  a.href = url;
+  a.download = filename;
+  document.body.append(a);
+  a.click();
+  a.remove();
+  URL.revokeObjectURL(url);
+}