fix(import): resolve correct id_articol for duplicate CODMATs + gestiune setting

Unified id_articol selection logic in Python (resolve_codmat_ids) and PL/SQL
(resolve_id_articol): filters sters=0 AND inactiv=0, prefers article with
stock in configured gestiune, falls back to MAX(id_articol). Eliminates
mismatch where Python and PL/SQL could pick different id_articol for the
same CODMAT, causing ORA-20000 price-not-found errors.

- Add resolve_codmat_ids helper in validation_service.py (single batch query)
- Refactor validate_skus/validate_prices/ensure_prices to use it
- Add resolve_id_articol function in PL/SQL package body
- Add p_id_gestiune parameter to importa_comanda (spec + body)
- Add /api/settings/gestiuni endpoint and id_gestiune setting
- Add gestiune dropdown in settings UI

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

api/app/templates/settings.html

@@ -38,6 +38,12 @@
         <div class="card h-100">
             <div class="card-header py-2 px-3 fw-semibold">Import ROA</div>
             <div class="card-body py-2 px-3">
+                <div class="mb-2">
+                    <label class="form-label mb-0 small">Gestiune (ID_GESTIUNE)</label>
+                    <select class="form-select form-select-sm" id="settIdGestiune">
+                        <option value="">— orice gestiune —</option>
+                    </select>
+                </div>
                 <div class="mb-2">
                     <label class="form-label mb-0 small">Secție (ID_SECTIE)</label>
                     <select class="form-select form-select-sm" id="settIdSectie">
@@ -146,5 +152,5 @@
 {% endblock %}
 
 {% block scripts %}
-<script src="{{ request.scope.get('root_path', '') }}/static/js/settings.js?v=3"></script>
+<script src="{{ request.scope.get('root_path', '') }}/static/js/settings.js?v=4"></script>
 {% endblock %}