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/services/expense_claim_pagination.py

@@ -0,0 +1,61 @@
+from __future__ import annotations
+
+from sqlalchemy import select
+from sqlalchemy.orm import selectinload
+
+from app.api.deps import CurrentUserContext
+from app.models.employee import Employee
+from app.models.financial_record import ExpenseClaim
+from app.services.pagination import PageResult, paginate_select
+
+
+class ExpenseClaimPaginationMixin:
+    def _claim_list_stmt(self):
+        return select(ExpenseClaim).options(
+            selectinload(ExpenseClaim.items),
+            selectinload(ExpenseClaim.employee).selectinload(Employee.manager),
+            selectinload(ExpenseClaim.employee).selectinload(Employee.roles),
+        )
+
+    def list_claims_page(
+        self,
+        current_user: CurrentUserContext,
+        *,
+        page: int | None,
+        page_size: int | None,
+    ) -> PageResult[ExpenseClaim]:
+        stmt = self._claim_list_stmt().order_by(
+            ExpenseClaim.created_at.desc(),
+            ExpenseClaim.occurred_at.desc(),
+        )
+        stmt = self._access_policy.apply_claim_scope(stmt, current_user)
+        return paginate_select(self.db, stmt, page=page, page_size=page_size)
+
+    def list_approval_claims_page(
+        self,
+        current_user: CurrentUserContext,
+        *,
+        page: int | None,
+        page_size: int | None,
+    ) -> PageResult[ExpenseClaim]:
+        stmt = self._claim_list_stmt().order_by(
+            ExpenseClaim.submitted_at.desc(),
+            ExpenseClaim.created_at.desc(),
+        )
+        stmt = self._access_policy.apply_approval_claim_scope(stmt, current_user)
+        return paginate_select(self.db, stmt, page=page, page_size=page_size)
+
+    def list_archived_claims_page(
+        self,
+        current_user: CurrentUserContext,
+        *,
+        page: int | None,
+        page_size: int | None,
+    ) -> PageResult[ExpenseClaim]:
+        stmt = self._claim_list_stmt().order_by(
+            ExpenseClaim.updated_at.desc(),
+            ExpenseClaim.submitted_at.desc(),
+            ExpenseClaim.created_at.desc(),
+        )
+        stmt = self._access_policy.apply_archived_claim_scope(stmt, current_user)
+        return paginate_select(self.db, stmt, page=page, page_size=page_size)