docs update, fix JSONL import (full-scan instead of line-offset tracking), sync button UX

wwwroot/app.js

@@ -543,13 +543,12 @@ async function syncData() {
   try {
     const res = await api('/api/sync', { method: 'POST' });
     btn.textContent = `↻ ${res.output}`;
-    setTimeout(() => { btn.textContent = '↻ Sync'; }, 3000);
     await loadView();
+    setTimeout(() => { btn.textContent = '↻ Sync'; btn.classList.remove('syncing'); }, 3000);
   } catch (e) {
     btn.textContent = '↻ Fehler!';
-    setTimeout(() => { btn.textContent = '↻ Sync'; }, 3000);
+    setTimeout(() => { btn.textContent = '↻ Sync'; btn.classList.remove('syncing'); }, 3000);
   }
-  btn.classList.remove('syncing');
 }
 
 // --- Modal ---