fix: 422 error on normal refresh — min query length violation

- Changed q=* to q=** in autocomplete.js and offline.js
- Backend requires min_query_length=2, single * was 1 char → 422
- Caused blank page on F5 refresh (non-hard-refresh)

frontend/js/autocomplete.js

@@ -314,7 +314,7 @@ function searchWikilinks(partial, callback) {
   }
 
   try {
-    fetch('/api/search/advanced?q=*&vault=all&limit=500')
+    fetch('/api/search/advanced?q=**&vault=all&limit=500')
       .then(function(r) { return r.json(); })
       .then(function(data) {
         _fileCache = (data.results || []).map(function(r) {

frontend/js/offline.js

@@ -72,7 +72,7 @@ export async function syncFileIndexFromServer() {
   }
   try {
     // Use a wildcard query to get recent files and populate offline index
-    const resp = await fetch('/api/search/advanced?q=*&vault=all&limit=200');
+    const resp = await fetch('/api/search/advanced?q=**&vault=all&limit=200');
     if (!resp.ok) {
       console.warn('[Offline] Index sync failed — API returned', resp.status);
       return;