fix: commit default campaign claim in ensure_admin_exists, surface setup errors to user

backend/app/auth.py

@@ -102,6 +102,7 @@ def ensure_admin_exists():
     # Claim the "default" campaign for the admin so setup wizard works
     admin = db.get_user_by_username(ADMIN_USERNAME)
     if admin:
+        with db.tx():
             conn.execute(
                 "UPDATE campaigns SET created_by = ? WHERE id = 'default' AND created_by IS NULL",
                 (admin["id"],),

frontend/src/pages/Setup.tsx

@@ -21,6 +21,8 @@ const DEFAULT_SETTINGS: Record<string, string> = {
 export default function Setup({ onComplete }: { onComplete: () => void }) {
   const [step, setStep] = useState(1);
   const [settings, setSettings] = useState<Record<string, string>>(DEFAULT_SETTINGS);
+  const [saving, setSaving] = useState(false);
+  const [error, setError] = useState("");
 
   // On first load, try to fetch existing settings from the "default" campaign
   // (which is always created by init_db).
@@ -36,9 +38,17 @@ export default function Setup({ onComplete }: { onComplete: () => void }) {
   const handleBack = () => setStep(prev => prev - 1);
 
   const handleSave = async () => {
+    setSaving(true);
+    setError("");
+    try {
       await api.updateCampaignSettings('default', settings);
       await api.updateSettings({ onboarding_completed: true });
       onComplete();
+    } catch (err: any) {
+      setError(err.message || "Failed to save settings");
+    } finally {
+      setSaving(false);
+    }
   };
 
   return (
@@ -213,12 +223,15 @@ export default function Setup({ onComplete }: { onComplete: () => void }) {
               )}
             </div>
 
+            {error && (
+              <div className="bg-red-900/50 border border-red-700 rounded px-4 py-3 text-red-200 text-sm">{error}</div>
+            )}
             <div className="flex justify-between pt-4 border-t border-slate-700">
-              <button onClick={handleBack} className="bg-slate-700 hover:bg-slate-600 text-white px-5 py-2 rounded font-medium">
+              <button onClick={handleBack} disabled={saving} className="bg-slate-700 hover:bg-slate-600 disabled:opacity-50 text-white px-5 py-2 rounded font-medium">
                 Back
               </button>
-              <button onClick={handleSave} className="bg-emerald-600 hover:bg-emerald-500 text-white px-5 py-2 rounded font-medium">
-                Complete Setup & Launch
+              <button onClick={handleSave} disabled={saving} className="bg-emerald-600 hover:bg-emerald-500 disabled:opacity-50 text-white px-5 py-2 rounded font-medium">
+                {saving ? "Saving…" : "Complete Setup & Launch"}
               </button>
             </div>
           </div>