chore: update demo username

store/db/seed/10001__user.sql

@@ -10,7 +10,7 @@ INSERT INTO
 VALUES
   (
     101,
-    'demohero',
+    'memos-demo',
     'HOST',
     'demo@usememos.com',
     'Derobot',

web/src/pages/Auth.tsx

@@ -32,7 +32,7 @@ const Auth = () => {
 
   useEffect(() => {
     if (mode === "demo") {
-      setUsername("demohero");
+      setUsername("memos-demo");
       setPassword("secret");
     }
   }, [mode]);