feat: 管理端专家管理完整CRUD(新增创建和删除)

后端:
- ExpertStore.create_expert: 创建专家(含bcrypt密码哈希)
- ExpertStore.delete_expert: 级联删除(咨询+服务关系+专家)
- POST /admin/experts: 创建专家API
- DELETE /admin/experts/{id}: 删除专家API

前端:
- AdminExperts页面加"新增专家"按钮和创建弹窗
- 创建弹窗含姓名/手机号/密码/分类/职称/简介/专长
- 每个专家卡片加删除按钮,二次确认后删除
- api.ts加adminCreateExpert和adminDeleteExpert方法

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

api.py

@@ -1644,6 +1644,44 @@ def admin_list_experts(status: str | None = None):
     return {"results": expert_store.list_experts(status=status)}
 
 
+class ExpertCreateRequest(BaseModel):
+    """创建专家请求。"""
+    name: str
+    phone: str
+    password: str
+    category: str
+    title: str = ""
+    bio: str = ""
+    expertise: str = ""
+    avatar_url: str | None = None
+    status: str = "active"
+
+
+@app.post("/admin/experts")
+def admin_create_expert(req: ExpertCreateRequest):
+    """管理端:创建专家(含登录账号)。"""
+    if len(req.password) < 6:
+        raise HTTPException(400, "密码至少 6 位")
+    try:
+        expert = expert_store.create_expert(
+            name=req.name, phone=req.phone, password=req.password,
+            category=req.category, title=req.title, bio=req.bio,
+            expertise=req.expertise, avatar_url=req.avatar_url,
+            status=req.status,
+        )
+    except ValueError as e:
+        raise HTTPException(400, str(e))
+    return {"created": True, "expert": expert}
+
+
+@app.delete("/admin/experts/{expert_id}")
+def admin_delete_expert(expert_id: int):
+    """管理端:删除专家(级联删除服务关系和咨询)。"""
+    if not expert_store.delete_expert(expert_id):
+        raise HTTPException(404, "专家不存在")
+    return {"deleted": True, "expert_id": expert_id}
+
+
 @app.patch("/admin/experts/{expert_id}/status")
 def admin_update_expert_status(expert_id: int, body: dict):
     """管理端:上架/下架专家。"""