refactor: 移除多租户相关代码，重构为单租户架构

此次提交进行了大规模的架构重构：
1.  移除所有平台租户相关模块和代码，包括租户管理、套餐、订单、发票等功能
2.  将菜单模块从platform迁移到system模块，统一系统功能入口
3.  移除租户隔离相关的模型混入、中间件和配置
4.  简化文件上传、SSE事件总线、定时任务等模块的租户逻辑
5.  重构所有业务schema和模型，移除租户相关字段和关联
6.  清理初始化脚本、模板和常量中的租户相关代码
7.  简化认证和权限控制逻辑，移除数据范围检查相关代码

backend/app/api/v1/module_system/dept/model.py

@@ -1,31 +1,23 @@
 from typing import TYPE_CHECKING
 
-from sqlalchemy import ForeignKey, Integer, String, Text, UniqueConstraint
+from sqlalchemy import ForeignKey, Integer, String, Text
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
-from app.common.enums import PermissionFilterStrategy
-from app.core.base_model import ModelMixin, TenantMixin, UserMixin
+from app.core.base_model import ModelMixin, UserMixin
 
 if TYPE_CHECKING:
     from app.api.v1.module_system.role.model import RoleModel
     from app.api.v1.module_system.user.model import UserModel
 
 
-class DeptModel(ModelMixin, TenantMixin, UserMixin):
+class DeptModel(ModelMixin, UserMixin):
     """部门模型
     """
 
     __tablename__: str = "sys_dept"
-    __table_args__ = (UniqueConstraint("tenant_id", "code"), {"comment": "部门表"})
+    __table_args__: dict[str, str] = {"comment": "部门表"}
     __tree_children_attr__: str = "children"
-    __loader_options__: list[str] = [
-        "children",
-        "created_by",
-        "updated_by",
-        "deleted_by",
-        "tenant_by",
-    ]
-    __permission_strategy__: PermissionFilterStrategy = PermissionFilterStrategy.DEPT_RELATION
+    __loader_options__: list[str] = ["children", "created_by", "updated_by", "deleted_by"]
 
     name: Mapped[str] = mapped_column(String(64), nullable=False, comment="部门名称")
     status: Mapped[int] = mapped_column(Integer, default=0, nullable=False, comment="状态(0:启动 1:停用)", index=True)

backend/app/api/v1/module_system/dept/schema.py

@@ -1,6 +1,6 @@
 from pydantic import BaseModel, ConfigDict, Field, field_validator
 
-from app.core.base_schema import BaseQueryParam, BaseSchema, TenantByQueryParam, TenantBySchema, UserByQueryParam, UserBySchema
+from app.core.base_schema import BaseQueryParam, BaseSchema, UserByQueryParam, UserBySchema
 from app.core.validator import validate_required_code
 
 
@@ -44,7 +44,7 @@ class DeptUpdateSchema(DeptCreateSchema):
     """部门更新模型"""
 
 
-class DeptOutSchema(DeptCreateSchema, BaseSchema, UserBySchema, TenantBySchema):
+class DeptOutSchema(DeptCreateSchema, BaseSchema, UserBySchema):
     """部门详情响应模型（不含 children，用于详情和更新）"""
 
     model_config = ConfigDict(from_attributes=True)
@@ -58,7 +58,7 @@ class DeptTreeOutSchema(DeptOutSchema):
     children: list["DeptTreeOutSchema"] | None = Field(default=None, description="子部门列表")
 
 
-class DeptQueryParam(BaseQueryParam, UserByQueryParam, TenantByQueryParam):
+class DeptQueryParam(BaseQueryParam, UserByQueryParam):
     """部门管理查询参数"""
 
     name: str | None = Field(None, description="部门名称")

backend/app/api/v1/module_system/dept/service.py

@@ -1,6 +1,5 @@
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.api.v1.module_platform.tenant.service import TenantService
 from app.core.base_schema import AuthSchema, BatchSetAvailable
 from app.core.exceptions import CustomException
 from app.utils.common_util import (
@@ -24,7 +23,7 @@ from .schema import (
 class DeptService:
     """部门管理服务
 
-    提供部门 CRUD、树形结构查询、级联启/禁用、租户配额检查等业务能力。
+    提供部门 CRUD、树形结构查询、级联启/禁用等业务能力。
     """
 
     def __init__(self, auth: AuthSchema, db: AsyncSession) -> None:
@@ -57,12 +56,6 @@ class DeptService:
         if obj:
             raise CustomException(msg="创建失败，编码已存在")
 
-        # 检查租户配额
-        user = self.auth.user
-        if not user:
-            raise CustomException(msg="未登录")
-        await TenantService(self.auth, self.db).check_quota(user.tenant_id, "dept")
-
         dept = await DeptCRUD(self.auth, self.db).create(data=data)
         return DeptOutSchema.model_validate(dept)