feat(admin): Phase 6 AI任务监控+成本异常 — 全局任务列/筛/详情抽屉/失败重投

后端:adminpanel tasks(全局 AITask + status/type/team/anomaly 筛分页)+ detail(payload)+ retry(失败重投,
仅图像类 best-effort 否则 400);is_cost_anomaly(实际>预估×1.5)+ F() 异常筛;IsPlatformAdmin + 审计。
前端:adminApi tasks 系列;Admin 任务监控页(状态 tab + 仅成本异常 chip + 表格成本预估→实际+异常标 + 详情抽屉 payload + 失败重投)。
修真 bug:抽屉缺 .show 类停屏外,补上正常滑入。
测试:adminpanel 36 单测过(筛/异常/详情/重投 mock celery + 非失败/不支持/权限拒);
无头 e2e _admin-p6.mjs 6 断言过 + 0 console error(不点真重投);tsc+build 绿。

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

core/backend/apps/adminpanel/serializers.py

@@ -1,9 +1,20 @@
+from decimal import Decimal
+
 from rest_framework import serializers
 
 from apps.accounts.models import Team, TeamMember, User
-from apps.ai.models import QualityWord
+from apps.ai.models import AITask, QualityWord
 from apps.assets.models import Asset
 
+# 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")
+
+
+def is_cost_anomaly(estimated, actual) -> bool:
+    est = estimated or Decimal("0")
+    act = actual or Decimal("0")
+    return bool(est > 0 and act > est * COST_ANOMALY_RATIO)
+
 
 class QualityWordSerializer(serializers.ModelSerializer):
     class Meta:
@@ -73,3 +84,29 @@ class AdminUserSerializer(serializers.ModelSerializer):
             {"team_id": str(m.team_id), "team_name": m.team.name, "role": m.role}
             for m in obj.team_memberships.select_related("team").all()
         ]
+
+
+class AdminTaskSerializer(serializers.ModelSerializer):
+    team_name = serializers.CharField(source="team.name", read_only=True, default=None)
+    model_name = serializers.CharField(source="model_config.name", read_only=True, default=None)
+    cost_anomaly = serializers.SerializerMethodField()
+
+    class Meta:
+        model = AITask
+        fields = [
+            "id", "task_type", "status", "team", "team_name", "model_name",
+            "estimated_cost", "actual_cost", "cost_anomaly", "error_code", "created_at",
+        ]
+        read_only_fields = fields
+
+    def get_cost_anomaly(self, obj) -> bool:
+        return is_cost_anomaly(obj.estimated_cost, obj.actual_cost)
+
+
+class AdminTaskDetailSerializer(AdminTaskSerializer):
+    class Meta(AdminTaskSerializer.Meta):
+        fields = AdminTaskSerializer.Meta.fields + [
+            "project", "idempotency_key", "request_payload", "response_payload",
+            "error_message", "submitted_at", "completed_at",
+        ]
+        read_only_fields = fields