feat(safety): invoice reconciliation on order detail

Add invoice total comparison in the order detail modal. When an order
has been invoiced, shows whether the invoice total matches the order
total — green badge if OK, red badge with difference amount if not.

Backend: compute reconciliation (difference, match) from existing
invoice.total_cu_tva vs order_total in order_detail endpoint.

Frontend: reconciliation badge below invoice info in modal, hidden
when no invoice exists.

Cache-bust: shared.js?v=17

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

api/app/routers/sync.py

@@ -456,6 +456,19 @@ async def order_detail(order_number: str):
         except Exception:
             pass
 
+    # Invoice reconciliation
+    inv = order.get("invoice")
+    if inv and inv.get("facturat") and inv.get("total_cu_tva") is not None:
+        order_total = float(order.get("order_total") or 0)
+        inv_total = float(inv["total_cu_tva"])
+        difference = round(inv_total - order_total, 2)
+        inv["reconciliation"] = {
+            "order_total": order_total,
+            "invoice_total": inv_total,
+            "difference": difference,
+            "match": abs(difference) < 0.01,
+        }
+
     # Parse discount_split JSON string
     if order.get("discount_split"):
         try: