feat(frontend): 增加订阅配额时间判断工具

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

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

frontend/src/types/index.ts

@@ -1480,6 +1480,7 @@ export interface UserSubscription {
   user_id: number
   group_id: number
   status: 'active' | 'expired' | 'revoked'
+  starts_at: string
   daily_usage_usd: number
   weekly_usage_usd: number
   monthly_usage_usd: number

frontend/src/utils/subscriptionQuota.ts

@@ -0,0 +1,42 @@
+import type { UserSubscription } from '@/types'
+
+const ONE_DAY_MS = 24 * 60 * 60 * 1000
+
+export interface RemainingDurationParts {
+  days: number
+  hours: number
+  minutes: number
+}
+
+export function isOneTimeDailyQuota(
+  subscription: Pick<UserSubscription, 'starts_at' | 'expires_at'>
+): boolean {
+  if (!subscription.starts_at || !subscription.expires_at) return false
+
+  const startsAt = new Date(subscription.starts_at).getTime()
+  const expiresAt = new Date(subscription.expires_at).getTime()
+
+  if (!Number.isFinite(startsAt) || !Number.isFinite(expiresAt)) return false
+
+  return expiresAt <= startsAt + ONE_DAY_MS
+}
+
+export function getRemainingDurationParts(
+  targetAt: Date | string,
+  now: Date = new Date()
+): RemainingDurationParts | null {
+  const targetTime = targetAt instanceof Date ? targetAt.getTime() : new Date(targetAt).getTime()
+  const nowTime = now.getTime()
+
+  if (!Number.isFinite(targetTime) || !Number.isFinite(nowTime)) return null
+
+  const diffMs = targetTime - nowTime
+  if (diffMs <= 0) return null
+
+  const totalMinutes = Math.floor(diffMs / (1000 * 60))
+  const days = Math.floor(totalMinutes / (24 * 60))
+  const hours = Math.floor((totalMinutes % (24 * 60)) / 60)
+  const minutes = totalMinutes % 60
+
+  return { days, hours, minutes }
+}