fix(codex): 修复额度窗口过期展示并补齐高覆盖测试

- 后端新增绝对重置时间字段计算（codex_5h_reset_at/codex_7d_reset_at）

- 前端统一窗口解析逻辑：绝对时间优先，updated_at+seconds 回退，过期自动归零

- 新增后端与前端单元测试，覆盖关键边界与异常场景

frontend/src/components/account/AccountUsageCell.vue

@@ -282,6 +282,7 @@ import { ref, computed, onMounted } from 'vue'
 import { useI18n } from 'vue-i18n'
 import { adminAPI } from '@/api/admin'
 import type { Account, AccountUsageInfo, GeminiCredentials, WindowStats } from '@/types'
+import { resolveCodexUsageWindow } from '@/utils/codexUsage'
 import UsageProgressBar from './UsageProgressBar.vue'
 import AccountQuotaInfo from './AccountQuotaInfo.vue'
 
@@ -326,153 +327,18 @@ const geminiUsageAvailable = computed(() => {
   )
 })
 
+const codex5hWindow = computed(() => resolveCodexUsageWindow(props.account.extra, '5h'))
+const codex7dWindow = computed(() => resolveCodexUsageWindow(props.account.extra, '7d'))
+
 // OpenAI Codex usage computed properties
 const hasCodexUsage = computed(() => {
-  const extra = props.account.extra
-  return (
-    extra &&
-    // Check for new canonical fields first
-    (extra.codex_5h_used_percent !== undefined ||
-      extra.codex_7d_used_percent !== undefined ||
-      // Fallback to legacy fields
-      extra.codex_primary_used_percent !== undefined ||
-      extra.codex_secondary_used_percent !== undefined)
-  )
+  return codex5hWindow.value.usedPercent !== null || codex7dWindow.value.usedPercent !== null
 })
 
-// 5h window usage (prefer canonical field)
-const codex5hUsedPercent = computed(() => {
-  const extra = props.account.extra
-  if (!extra) return null
-
-  // Prefer canonical field
-  if (extra.codex_5h_used_percent !== undefined) {
-    return extra.codex_5h_used_percent
-  }
-
-  // Fallback: detect from legacy fields using window_minutes
-  if (
-    extra.codex_primary_window_minutes !== undefined &&
-    extra.codex_primary_window_minutes <= 360
-  ) {
-    return extra.codex_primary_used_percent ?? null
-  }
-  if (
-    extra.codex_secondary_window_minutes !== undefined &&
-    extra.codex_secondary_window_minutes <= 360
-  ) {
-    return extra.codex_secondary_used_percent ?? null
-  }
-
-  // Legacy assumption: secondary = 5h (may be incorrect)
-  return extra.codex_secondary_used_percent ?? null
-})
-
-const codex5hResetAt = computed(() => {
-  const extra = props.account.extra
-  if (!extra) return null
-
-  // Prefer canonical field
-  if (extra.codex_5h_reset_after_seconds !== undefined) {
-    const resetTime = new Date(Date.now() + extra.codex_5h_reset_after_seconds * 1000)
-    return resetTime.toISOString()
-  }
-
-  // Fallback: detect from legacy fields using window_minutes
-  if (
-    extra.codex_primary_window_minutes !== undefined &&
-    extra.codex_primary_window_minutes <= 360
-  ) {
-    if (extra.codex_primary_reset_after_seconds !== undefined) {
-      const resetTime = new Date(Date.now() + extra.codex_primary_reset_after_seconds * 1000)
-      return resetTime.toISOString()
-    }
-  }
-  if (
-    extra.codex_secondary_window_minutes !== undefined &&
-    extra.codex_secondary_window_minutes <= 360
-  ) {
-    if (extra.codex_secondary_reset_after_seconds !== undefined) {
-      const resetTime = new Date(Date.now() + extra.codex_secondary_reset_after_seconds * 1000)
-      return resetTime.toISOString()
-    }
-  }
-
-  // Legacy assumption: secondary = 5h
-  if (extra.codex_secondary_reset_after_seconds !== undefined) {
-    const resetTime = new Date(Date.now() + extra.codex_secondary_reset_after_seconds * 1000)
-    return resetTime.toISOString()
-  }
-
-  return null
-})
-
-// 7d window usage (prefer canonical field)
-const codex7dUsedPercent = computed(() => {
-  const extra = props.account.extra
-  if (!extra) return null
-
-  // Prefer canonical field
-  if (extra.codex_7d_used_percent !== undefined) {
-    return extra.codex_7d_used_percent
-  }
-
-  // Fallback: detect from legacy fields using window_minutes
-  if (
-    extra.codex_primary_window_minutes !== undefined &&
-    extra.codex_primary_window_minutes >= 10000
-  ) {
-    return extra.codex_primary_used_percent ?? null
-  }
-  if (
-    extra.codex_secondary_window_minutes !== undefined &&
-    extra.codex_secondary_window_minutes >= 10000
-  ) {
-    return extra.codex_secondary_used_percent ?? null
-  }
-
-  // Legacy assumption: primary = 7d (may be incorrect)
-  return extra.codex_primary_used_percent ?? null
-})
-
-const codex7dResetAt = computed(() => {
-  const extra = props.account.extra
-  if (!extra) return null
-
-  // Prefer canonical field
-  if (extra.codex_7d_reset_after_seconds !== undefined) {
-    const resetTime = new Date(Date.now() + extra.codex_7d_reset_after_seconds * 1000)
-    return resetTime.toISOString()
-  }
-
-  // Fallback: detect from legacy fields using window_minutes
-  if (
-    extra.codex_primary_window_minutes !== undefined &&
-    extra.codex_primary_window_minutes >= 10000
-  ) {
-    if (extra.codex_primary_reset_after_seconds !== undefined) {
-      const resetTime = new Date(Date.now() + extra.codex_primary_reset_after_seconds * 1000)
-      return resetTime.toISOString()
-    }
-  }
-  if (
-    extra.codex_secondary_window_minutes !== undefined &&
-    extra.codex_secondary_window_minutes >= 10000
-  ) {
-    if (extra.codex_secondary_reset_after_seconds !== undefined) {
-      const resetTime = new Date(Date.now() + extra.codex_secondary_reset_after_seconds * 1000)
-      return resetTime.toISOString()
-    }
-  }
-
-  // Legacy assumption: primary = 7d
-  if (extra.codex_primary_reset_after_seconds !== undefined) {
-    const resetTime = new Date(Date.now() + extra.codex_primary_reset_after_seconds * 1000)
-    return resetTime.toISOString()
-  }
-
-  return null
-})
+const codex5hUsedPercent = computed(() => codex5hWindow.value.usedPercent)
+const codex5hResetAt = computed(() => codex5hWindow.value.resetAt)
+const codex7dUsedPercent = computed(() => codex7dWindow.value.usedPercent)
+const codex7dResetAt = computed(() => codex7dWindow.value.resetAt)
 
 // Antigravity quota types (用于 API 返回的数据)
 interface AntigravityUsageResult {