PALETTE: swatch preview + tooltip + OK commit — TDD

Clicking a swatch instantly swaps the body palette class for a live
preview; OK commits silently (POST, no reload); click-elsewhere or
10 s auto-dismiss reverts. Tooltip portal shows label, shoptalk,
lock state. Locked swatches show × (disabled). 20 FTs green.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/templates/apps/dashboard/home.html

@@ -20,5 +20,6 @@
             {% include "apps/dashboard/_partials/_applets.html" %}
             {% include "apps/applets/_partials/_gear.html" with menu_id="id_dash_applet_menu" %}
         </div>
+        <div id="id_tooltip_portal" class="token-tooltip" style="display:none;"></div>
     {% endif %}
 {% endblock content %}