feat(task): 任务中心扫码接单(多端) —— 服务端任务状态机/端口/迁移

- Task 加 task_code/tags/display_priority/claimed_by/claimed_at/doing_at；新增 TaskClaim 流水表。
- TaskService 加 claimed/doing/completed 状态机(claim/start_doing/complete)，grab 并入 claim。
- TaskRepository 加 list_published/get_by_code/update/claim/set_doing + TaskClaimRepository；挂 Database。
- 端口：
  · opc  /tasks/grab-by-code、/tasks/{id}/doing、/tasks/{id}/complete
  · operator POST /tasks(auto task_code) + PATCH /tasks/:id
  · park  /park/api/tasks(大屏展示,含 scan_payload 二维码载荷)
  · training /api/tasks/claim-by-code、/api/tasks/my(小程序 C 端账号→OPC 身份 find-or-create 领单)
- 迁移 0008(tasks 加列 + task_claims)已应用+stamp；seed 补 task_code/tags/grab demo。
- tests/test_task_claim.py(自包含内存库, 状态机+流水+list_published), 直接 async 校验通过。

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

app/api/schemas/operator.py

@@ -5,16 +5,33 @@ class TaskCreateRequest(BaseModel):
     category: str = ""
     sub_category: str = ""
     description: str = ""
+    tags: str = ""
     mode: str = "grab"
     budget_min: int = 0
     budget_max: int = 0
     deadline: str = ""
+    task_code: str = ""
+    display_priority: int = 0
     publisher_name: str = ""
 
 
+class TaskUpdateRequest(BaseModel):
+    title: str | None = None
+    category: str | None = None
+    sub_category: str | None = None
+    description: str | None = None
+    tags: str | None = None
+    mode: str | None = None
+    budget_min: int | None = None
+    budget_max: int | None = None
+    deadline: str | None = None
+    task_code: str | None = None
+    display_priority: int | None = None
+    publisher_name: str | None = None
+
 
 class TaskStatusRequest(BaseModel):
-    status: str  # review/published/completed/cancelled
+    status: str  # review/published/completed/cancelled/claimed/doing
 
 
 
@@ -81,6 +98,22 @@ class CourseStatusRequest(BaseModel):
     status: str  # draft/published/ended/offline
 
 
+class ActivityCreateRequest(BaseModel):
+    title: str
+    type: str | None = None          # free/salon
+    mode: str | None = None          # online/offline
+    status: str | None = None        # open/invite/pending/done/ended
+    subtitle: str | None = None
+    desc: str | None = None
+    location: str | None = None
+    host: str | None = None
+    image: str | None = None
+    link: str | None = None
+    start_at: str | None = None
+    duration_min: int | None = None
+    capacity: int | None = None
+
+
 class ActivityStatusRequest(BaseModel):
     status: str  # open/invite/pending/done/ended