v2.0.4 - Fix Users page edit and add bugs

Bug Fixes

• Fixed a bug where saving changes on the Edit User form (admin.php?func=users) returned a blank page instead of the users list.
• Fixed a bug where adding a new user with the Administrator option unchecked silently failed and no account was created.

Root Cause

• Edit save: The post-update redirect back to the users list was commented out, so after the UPDATE ran the module rendered no content, leaving a blank page.
• Add user: The users.superuser column is INTEGER NOT NULL. The add handler passed the superuser checkbox value straight into the INSERT, so when the box was left unchecked the field was absent from the request and NULL was bound, triggering a NOT NULL constraint violation that aborted the insert.

Changes

• Restored the post-update redirect on the Users edit action in admin.php
• Normalized the superuser checkbox to "1"/"0" before the add INSERT and in its audit log entry, matching the existing edit handler