feat: 统一后端分页查询与前端服务层适配

后端新增通用分页模块，为报销单、员工、预算、agent 资产等
端点统一接入分页参数和游标查询，优化 repository 层分页实
现，前端服务层适配分页响应结构，完善预算图表和全局样式，
优化侧边栏和企业选择器组件，引入 Element Plus 插件注册。

server/src/app/repositories/employee.py

@@ -6,13 +6,14 @@ from sqlalchemy.orm import Session, selectinload
 from app.models.employee import Employee
 from app.models.organization import OrganizationUnit
 from app.models.role import Role
+from app.services.pagination import PageResult, paginate_select
 
 
 class EmployeeRepository:
     def __init__(self, db: Session) -> None:
         self.db = db
 
-    def list(self, status: str | None = None, keyword: str | None = None) -> list[Employee]:
+    def _list_stmt(self, status: str | None = None, keyword: str | None = None):
         stmt = (
             select(Employee)
             .options(
@@ -38,8 +39,23 @@ class EmployeeRepository:
                 )
             )
 
+        return stmt
+
+    def list(self, status: str | None = None, keyword: str | None = None) -> list[Employee]:
+        stmt = self._list_stmt(status=status, keyword=keyword)
         return list(self.db.execute(stmt).scalars().unique().all())
 
+    def list_page(
+        self,
+        *,
+        status: str | None = None,
+        keyword: str | None = None,
+        page: int | None,
+        page_size: int | None,
+    ) -> PageResult[Employee]:
+        stmt = self._list_stmt(status=status, keyword=keyword)
+        return paginate_select(self.db, stmt, page=page, page_size=page_size, unique=True)
+
     def get(self, employee_id: str) -> Employee | None:
         stmt = (
             select(Employee)