feat: enhance layout components, data layer and global styles

- SidebarRail, TopBar, FilterBar: improved navigation and filtering UX

- metrics.js, requests.js: expanded data with multi-range trend series

- composables: enhanced useChat, useNavigation, useRequests

- global.css: refined design tokens and utility classes

- Add DocFilterBar component and LoginView page

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/composables/useNavigation.js

@@ -2,11 +2,46 @@ import { computed, ref } from 'vue'
 import { icons } from '../data/icons.js'
 
 export const navItems = [
-  { id: 'overview', label: '运营总览', icon: icons.dashboard, title: '企业报销智能运营台', desc: '面向财务共享中心的审批、风控、SLA 与智能体协同工作台。' },
-  { id: 'chat', label: '合规对话', icon: icons.message, title: 'AI 合规对话', desc: '上传单据、追问制度依据，并生成可留痕的审核建议。' },
-  { id: 'requests', label: '报销队列', icon: icons.list, title: '报销申请队列', desc: '按风险、补件状态和 AI 建议处理待审单据。' },
-  { id: 'policies', label: '政策规则', icon: icons.file, title: '政策规则中心', desc: '维护差旅、招待、采购和发票校验规则。' },
-  { id: 'audit', label: '审计追踪', icon: icons.audit, title: '审计追踪', desc: '查看关键审批动作、AI 建议和制度命中记录。' }
+  {
+    id: 'overview',
+    label: '总览',
+    navHint: '运营指标与趋势',
+    icon: icons.dashboard,
+    title: '企业报销智能运营台',
+    desc: '面向财务共享中心的审批、风控、SLA与自动化运营看板'
+  },
+  {
+    id: 'chat',
+    label: '审批中心',
+    navHint: 'AI 助手与单据处理',
+    icon: icons.message,
+    title: '单据管理中心',
+    desc: '管理出差申请、报销单据，AI 辅助发起申请与智能审核。'
+  },
+  {
+    id: 'requests',
+    label: '报销单',
+    navHint: '待审队列与风险处理',
+    icon: icons.list,
+    title: '报销申请队列',
+    desc: '按风险、补件状态和 AI 建议处理待审单据。'
+  },
+  {
+    id: 'policies',
+    label: '政策规则',
+    navHint: '制度与校验规则',
+    icon: icons.file,
+    title: '政策规则中心',
+    desc: '维护差旅、招待、采购和发票校验规则。'
+  },
+  {
+    id: 'audit',
+    label: '审计追踪',
+    navHint: '关键动作与日志',
+    icon: icons.audit,
+    title: '审计追踪',
+    desc: '查看关键审批动作、AI 建议和制度命中记录。'
+  }
 ]
 
 export function useNavigation() {