feat(admin): Phase 7 计费审计+4层额度策略 — 流水浏览/手动调额/额度策略CRUD+拦截

后端:adminpanel ledgers(全局流水+筛)+ adjust(手动调额,落 ADJUSTMENT)+ quota-policies CRUD;
额度拦截 _enforce_quota_policy(单任务/月度/项目)接入 reserve_credit,仅团队有 active 策略才生效(无策略零回归);
adjust_credit helper。修真 bug:log_admin_action 加 savepoint + JSON 安全化(UUID/Decimal),
修复传 serializer.data 致审计报错污染外层事务 → TransactionManagementError。
前端:adminApi 计费/额度系列;计费审计页(流水表+手动调额弹窗)+ 额度策略页(CRUD 弹窗,团队下拉+三类上限+启用)。
测试:adminpanel 44 + billing + accounts = 70 单测过(调额±/超额拒/额度拦截 per_task+monthly/无策略零回归);
无头 e2e _admin-p7.mjs 6 断言过 + 0 console error(一次性团队,不动 demo 余额);tsc+build 绿。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/backend/apps/adminpanel/serializers.py

@@ -5,6 +5,7 @@ from rest_framework import serializers
 from apps.accounts.models import Team, TeamMember, User
 from apps.ai.models import AITask, QualityWord
 from apps.assets.models import Asset
+from apps.billing.models import CreditLedger, QuotaPolicy
 
 # 成本异常阈值:实际成本 > 预估 × 此倍数(且预估 > 0)即标异常
 COST_ANOMALY_RATIO = Decimal("1.5")
@@ -110,3 +111,25 @@ class AdminTaskDetailSerializer(AdminTaskSerializer):
             "error_message", "submitted_at", "completed_at",
         ]
         read_only_fields = fields
+
+
+class AdminLedgerSerializer(serializers.ModelSerializer):
+    team_name = serializers.CharField(source="team.name", read_only=True, default=None)
+    username = serializers.CharField(source="user.username", read_only=True, default=None)
+
+    class Meta:
+        model = CreditLedger
+        fields = ["id", "team", "team_name", "username", "ledger_type", "amount", "balance_after", "reason", "created_at"]
+        read_only_fields = fields
+
+
+class AdminQuotaPolicySerializer(serializers.ModelSerializer):
+    team_name = serializers.CharField(source="team.name", read_only=True, default=None)
+
+    class Meta:
+        model = QuotaPolicy
+        fields = [
+            "id", "team", "team_name", "user", "project",
+            "monthly_limit", "project_limit", "per_task_limit", "is_active", "created_at",
+        ]
+        read_only_fields = ["id", "team_name", "created_at"]