fix(nginxproxymanager): update for better-sqlite3 and setup wizard

NPM switched to better-sqlite3 as the knex database client.
The old sqlite3 client causes 'Internal Error' on user creation.

- Update production.json in install/update to use better-sqlite3
- Add sed patch in update script to fix existing production.json
- Add useNullAsDefault: true to match upstream knex config
- Remove default credentials from JSON (NPM now uses setup wizard)
- Add note about setup wizard for first-time users

Ref: NginxProxyManager/nginx-proxy-manager@0b2fa82
Closes #11681

install/nginxproxymanager-install.sh

@@ -130,10 +130,11 @@ if [ ! -f /app/config/production.json ]; then
   "database": {
     "engine": "knex-native",
     "knex": {
-      "client": "sqlite3",
+      "client": "better-sqlite3",
       "connection": {
         "filename": "/data/database.sqlite"
-      }
+      },
+      "useNullAsDefault": true
     }
   }
 }