fix: refine mobile navigation and settings

frontend/src/lib/mvp-utils.ts

@@ -369,6 +369,59 @@ export function habitActionState(cell?: { scheduled?: boolean; paused?: boolean
   return { writable: true, reason: '' }
 }
 
+export function formatUserAgent(userAgent?: string | null): string {
+  const ua = userAgent?.trim() ?? ''
+  let device = '未知设备'
+  if (/iPhone/i.test(ua)) device = 'iPhone'
+  else if (/iPad/i.test(ua) || (/Macintosh/i.test(ua) && /Mobile/i.test(ua))) device = 'iPad'
+  else if (/Android/i.test(ua) && /Mobile/i.test(ua)) device = 'Android 手机'
+  else if (/Android/i.test(ua)) device = 'Android 平板'
+  else if (/Windows/i.test(ua)) device = 'Windows'
+  else if (/Macintosh|Mac OS X/i.test(ua)) device = 'Mac'
+  else if (/Linux/i.test(ua)) device = 'Linux'
+
+  let browser = '未知浏览器'
+  if (/Edg(?:e|iOS|A)?\//i.test(ua)) browser = 'Edge'
+  else if (/Chrome\/|CriOS\//i.test(ua)) browser = 'Chrome'
+  else if (/Firefox\/|FxiOS\//i.test(ua)) browser = 'Firefox'
+  else if (/Safari\//i.test(ua) && /Version\//i.test(ua)) browser = 'Safari'
+  return `${device} · ${browser}`
+}
+
+export function formatLocalShortDateTime(value?: string | null, options: { timeZone?: string } = {}): string {
+  const source = value?.trim()
+  if (!source) return '未知时间'
+  const calendar = /^(\d{4})-(\d{2})-(\d{2})T/.exec(source)
+  if (calendar) {
+    const [, year, month, day] = calendar
+    const probe = new Date(Date.UTC(Number(year), Number(month) - 1, Number(day)))
+    if (probe.getUTCFullYear() !== Number(year) || probe.getUTCMonth() + 1 !== Number(month) || probe.getUTCDate() !== Number(day)) return '未知时间'
+  }
+  const timezoneLess = /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}(?::\d{2}(?:\.\d{1,9})?)?$/i.test(source)
+  const date = new Date(timezoneLess ? `${source}Z` : source)
+  if (Number.isNaN(date.getTime())) return '未知时间'
+  try {
+    return new Intl.DateTimeFormat('zh-CN', { dateStyle: 'short', timeStyle: 'short', ...options }).format(date)
+  } catch {
+    return '未知时间'
+  }
+}
+
+const AUDIT_ACTIONS: Record<string, string> = {
+  create: '创建', update: '更新', complete: '完成', delete: '删除', archive: '归档', restore: '恢复', move: '移动', import: '导入',
+}
+const AUDIT_ENTITIES: Record<string, string> = {
+  task: '任务', list: '清单', folder: '文件夹', countdown: '倒数日', backup: '备份',
+}
+
+export function formatAuditAction(action?: string | null): string {
+  return action ? AUDIT_ACTIONS[action.toLowerCase()] ?? '其他操作' : '其他操作'
+}
+
+export function formatAuditEntity(entityType?: string | null): string {
+  return entityType ? AUDIT_ENTITIES[entityType.toLowerCase()] ?? '内容' : '内容'
+}
+
 export function formatHabitApiError(detail: unknown): string {
   const source = detail && typeof detail === 'object' && !Array.isArray(detail) && 'detail' in detail
     ? (detail as Record<string, unknown>).detail