fix: correct DB health fix button action from fix_schema to fix_db

templates/admin/settings.html

@@ -196,7 +196,7 @@
         {% if health.missing_columns %}
         <p>Missing columns: {{ health.missing_columns | join(', ') }}</p>
         <form method="POST" action="{{ url_for('admin_settings') }}">
-          <input type="hidden" name="action" value="fix_schema">
+          <input type="hidden" name="action" value="fix_db">
           <button type="submit">Fix Missing Columns</button>
         </form>
         {% endif %}