IT Assets: remove manual user creation from settings

Users are sourced exclusively from the portal (via SSO auto-create or
the Sync from Portal button). The Add User form and create_admin route
are removed to prevent out-of-sync local-only accounts.
A footer hint now links admins to the portal settings page.

IT_asset_management/app/routes/settings.py

@@ -15,35 +15,6 @@ def index():
     return render_template('settings/index.html', admins=admins, config=current_app.config)
 
 
-@bp.route('/admin/new', methods=['POST'])
-@login_required
-@admin_required
-def create_admin():
-    username = request.form.get('username', '').strip()
-    email = request.form.get('email', '').strip()
-    full_name = request.form.get('full_name', '').strip()
-    password = request.form.get('password', '')
-    role = request.form.get('role', 'readonly')
-
-    if role not in ('admin', 'editor', 'readonly'):
-        role = 'readonly'
-
-    if not username or not email or not password:
-        flash('Username, email and password are required.', 'danger')
-        return redirect(url_for('settings.index'))
-
-    if AdminUser.query.filter_by(username=username).first():
-        flash(f'Username "{username}" is already taken.', 'danger')
-        return redirect(url_for('settings.index'))
-
-    admin = AdminUser(username=username, email=email, full_name=full_name, role=role)
-    admin.set_password(password)
-    db.session.add(admin)
-    db.session.commit()
-    flash(f'User "{username}" created with role "{role}".', 'success')
-    return redirect(url_for('settings.index'))
-
-
 @bp.route('/admin/<int:admin_id>/toggle', methods=['POST'])
 @login_required
 @admin_required