feat(partner): detect and resync partner mismatches on already-imported orders

Detects PF↔PJ transitions and CUI changes after import; auto-resyncs
uninvoiced orders (max 5/cycle) and shows visual alert for invoiced ones.
- SQLite: partner_mismatch column + batch helpers
- sync_service: detection loop + _resync_partner_for_order
- dashboard: red dot + attention card indicator
- modal: alert with contextual message and resync button

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

api/app/templates/base.html

@@ -120,6 +120,8 @@
                             </div>
                         </div>
                     </div>
+                    <!-- Partner mismatch alert -->
+                    <div id="detailPartnerMismatch" style="display:none" class="mb-2"></div>
                     <!-- Denomination mismatch alert -->
                     <div id="detailDenomMismatch" style="display:none" class="mb-2"></div>
                     <!-- Compact Address Lines -->