feat(order-detail): show CODMAT for direct SKUs + mapping validations

- Enrich order detail items with NOM_ARTICOLE data for direct SKUs
  (SKU=CODMAT) that have no ARTICOLE_TERTI entry
- Validate CODMAT exists in nomenclator before saving mapping (400)
- Block redundant self-mapping when SKU is already direct CODMAT (409)
- Show "direct" badge in CODMAT column for direct SKUs
- Show info alert in quick map modal for direct SKUs
- Display backend validation errors inline in modal

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

api/app/templates/dashboard.html

@@ -192,11 +192,12 @@
                 <button type="button" class="btn btn-sm btn-outline-secondary mt-1" onclick="addQmCodmatLine()" style="font-size:0.8rem; padding:2px 10px">
                     + CODMAT
                 </button>
+                <div id="qmDirectInfo" class="alert alert-info mt-2" style="display:none; font-size:0.85rem; padding:8px 12px;"></div>
                 <div id="qmPctWarning" class="text-danger mt-2" style="display:none;"></div>
             </div>
             <div class="modal-footer">
                 <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Anuleaza</button>
-                <button type="button" class="btn btn-primary" onclick="saveQuickMapping()">Salveaza</button>
+                <button type="button" class="btn btn-primary" id="qmSaveBtn" onclick="saveQuickMapping()">Salveaza</button>
             </div>
         </div>
     </div>
@@ -204,5 +205,5 @@
 {% endblock %}
 
 {% block scripts %}
-<script src="{{ request.scope.get('root_path', '') }}/static/js/dashboard.js?v=15"></script>
+<script src="{{ request.scope.get('root_path', '') }}/static/js/dashboard.js?v=16"></script>
 {% endblock %}