fix(receivables): unwrap response envelope once + align card/column field names

- Receivables.vue: const d = r (was r.data || r) -> cards/table no longer blank

- cards: pending_balance(待收余额) / overdue / completed_amount / completed_count

- columns: counterparty(+description fallback) / owner(未分配) / settled_amount / plan_date / aging_bucket

- cash.py: summary.completed_count + _plan_dict.settled_amount (existing keys untouched)

- api/index.ts untouched (global interceptor)

(cherry picked from commit d60557622441b971970fb9dc86ef7491c3a9d72b)

backend/app/api/cash.py

@@ -68,6 +68,7 @@ def _plan_dict(p: CashPlan) -> dict:
         "plan_type_label": "收款" if p.plan_type == "receive" else "付款",
         "amount": round(p.amount or 0, 2),
         "paid_amount": paid,
+        "settled_amount": round(p.amount or 0, 2) if p.status == "completed" else paid,
         "receivable_balance": max(balance, 0),
         "plan_date": p.plan_date.strftime("%Y-%m-%d") if p.plan_date else "",
         "counterparty": p.counterparty or "",
@@ -583,6 +584,7 @@ def api_receivables(
     overdue_amount = 0.0
     aging_amount = {}
     completed_amount = 0.0
+    completed_count = 0
     for p in plans:
         d = _plan_dict(p)
         if status:
@@ -605,6 +607,7 @@ def api_receivables(
             aging_amount[d["aging_bucket"]] = aging_amount.get(d["aging_bucket"], 0) + d["receivable_balance"]
         elif d["status"] == "completed":
             completed_amount += d["amount"]
+            completed_count += 1
 
     owners = [r[0] for r in db.query(CashPlan.owner).filter(
         CashPlan.entity_id == entity_id,
@@ -625,6 +628,7 @@ def api_receivables(
             "overdue_count": overdue_count,
             "overdue_amount": round(overdue_amount, 2),
             "completed_amount": round(completed_amount, 2),
+            "completed_count": completed_count,
             "aging": {k: round(v, 2) for k, v in sorted(aging_amount.items(), key=lambda x: x[0])},
         },
         "data": items,