fix(extract): 实体提取改异步(worker+轮询),根治 502 + 刷新丢 loading + 重复扣费

问题:进资产页点"提取人物/场景"——同步死等豆包思考模型(数十秒)→ 撞网关超时
502;"提取中"loading 是纯前端内存态,刷新即丢;且无幂等,刷新后重点会重复扣费。

改动(对齐全站异步三件套:出图/三视图/故事板同款):
- 后端 submit_extract_entities:Web 只建 RESERVED 任务 + 预留额度秒回(不再 502);
  已有在途提取则复用,绝不二次预扣(防刷新后重点 / 并发重复扣费)。
- 后端 run_extract_entities_task(Celery worker):流式调豆包 + 解析 + 落库 + 扣费;
  失败退费并把可读错误记进 task.error_message。
- 新增 AITask.Type.entity_extraction(迁移 0011)+ extract-status 端点(轮询进度/成败)。
- 前端 runExtract 改提交+轮询;进资产页自动认领在途提取,刷新后 loading 自己回来。

验收:完整 Django 套件 149/149 全绿(含新增 4 测:异步落库+计费一次 / content空
回退 reasoning / 在途防重复扣费 / 状态端点成败透出);tsc + vite build 全绿;
makemigrations --check 无遗漏。

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

core/backend/apps/projects/tests.py

@@ -4,7 +4,7 @@ from unittest.mock import patch
 from rest_framework.test import APIClient
 
 from apps.accounts.models import Team, TeamMember, User
-from apps.ai.models import ModelConfig, ModelProvider
+from apps.ai.models import AITask, ModelConfig, ModelProvider
 from apps.assets.models import Asset
 from apps.billing.models import CreditAccount, CreditLedger
 from apps.products.models import Product
@@ -205,6 +205,53 @@ class ProjectApiTests(TestCase):
         project.refresh_from_db()
         self.assertIn("男主", project.metadata.get("cast", []))
 
+    @patch("apps.ai.services.VolcanoArkProvider")
+    def test_extract_entities_inflight_guard_reuses_task(self, provider_cls):
+        """已有在途提取任务时再次提交 → 复用同一任务,不新建、不二次预扣、不重跑模型
+        (用户刷新后手痒重点 / 并发点击都不会重复扣费)。"""
+        from apps.ai.services import submit_extract_entities
+
+        project = Project.objects.create(team=self.team, created_by=self.user, product=self.product, name="P3")
+        script = ScriptVersion.objects.create(
+            project=project, title="脚本", content="x", is_adopted=True, metadata={"entities": []},
+        )
+        ScriptSegment.objects.create(script_version=script, sort_order=0, narration="旧0", visual_prompt="画0")
+        inflight = AITask.objects.create(
+            team=self.team, created_by=self.user, project=project, model_config=self.model,
+            task_type=AITask.Type.ENTITY_EXTRACTION, status=AITask.Status.SUBMITTED,
+            idempotency_key="entity_extraction:inflight:1",
+        )
+        before = AITask.objects.filter(project=project, task_type=AITask.Type.ENTITY_EXTRACTION).count()
+
+        task = submit_extract_entities(project=project, user=self.user)
+        self.assertEqual(str(task.id), str(inflight.id))  # 复用在途任务
+        self.assertEqual(  # 没新建任务
+            AITask.objects.filter(project=project, task_type=AITask.Type.ENTITY_EXTRACTION).count(), before
+        )
+        provider_cls.return_value.chat_completion_stream.assert_not_called()  # 没重跑模型
+        # 没二次预扣额度(复用直接 return,根本没走到 create_ai_task)
+        self.assertEqual(CreditLedger.objects.filter(team=self.team, ledger_type=CreditLedger.Type.RESERVE).count(), 0)
+
+    def test_extract_status_reports_running_then_failure(self):
+        """extract-status:在途→running=True;失败→running=False 且把可读错误透给前端(刷新后也能看到失败原因)。"""
+        project = Project.objects.create(team=self.team, created_by=self.user, product=self.product, name="P4")
+        t = AITask.objects.create(
+            team=self.team, created_by=self.user, project=project, model_config=self.model,
+            task_type=AITask.Type.ENTITY_EXTRACTION, status=AITask.Status.SUBMITTED,
+            idempotency_key="entity_extraction:status:1",
+        )
+        res = self.client.get(f"/api/projects/{project.id}/extract-status/")
+        self.assertEqual(res.status_code, 200)
+        self.assertTrue(res.data["running"])
+
+        t.status = AITask.Status.FAILED
+        t.error_message = "提取结果解析失败(模型未返回有效 JSON),请重试"
+        t.save(update_fields=["status", "error_message"])
+        res = self.client.get(f"/api/projects/{project.id}/extract-status/")
+        self.assertFalse(res.data["running"])
+        self.assertEqual(res.data["status"], "failed")
+        self.assertIn("未返回有效 JSON", res.data["error"])
+
     @patch("apps.ai.services._store_generated_media")
     @patch("apps.ai.services.get_image_provider")
     def test_generate_base_asset_stores_tag_label(self, get_provider, store_media):