Expand admin dashboard with trends, health, study and email insights; v2.8.0

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

server/routes/nuggets-host-upload.js

@@ -108,7 +108,7 @@ async function saveUploadHosts(data) {
 }
 
 // ── History helpers ───────────────────────────────────────────────────────
-async function loadHistory() {
+export async function loadHistory() {
   try {
     const raw = await readFile(NUGGETS_UPLOAD_HISTORY_FILE, 'utf8')
     return JSON.parse(raw)