feat(admin): 新增统一时间格式化 formatDateTime（YYYY-MM-DD HH:mm:ss）

admin-frontend-vue/src/utils/datetime.ts

@@ -0,0 +1,45 @@
+/**
+ * 后台统一时间展示：字符串「YYYY-MM-DD HH:mm:ss」。
+ * 兼容 Java/MySQL 常见形态：ISO 带 T / 带毫秒 / 纯数字秒或毫秒 / Date 实例。
+ */
+export function formatDateTime(value: unknown, fallback = '—'): string {
+  if (value == null || value === '') return fallback
+  if (value instanceof Date) {
+    if (Number.isNaN(value.getTime())) return fallback
+    return padDate(value)
+  }
+  const raw = String(value).trim()
+  if (!raw) return fallback
+  // 已是目标格式
+  if (/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}$/.test(raw)) return raw
+  const match = /^(\d{4})-(\d{2})-(\d{2})[T ](\d{1,2}):(\d{2})(?::(\d{2}))?/.exec(raw)
+  if (match) {
+    const [, y, mo, d, h, mi, s] = match
+    return `${y}-${mo}-${d} ${pad(h)}:${mi}:${s ?? '00'}`
+  }
+  const dateOnly = /^(\d{4})-(\d{2})-(\d{2})$/.exec(raw)
+  if (dateOnly) return `${dateOnly[1]}-${dateOnly[2]}-${dateOnly[3]} 00:00:00`
+  if (/^\d+$/.test(raw)) {
+    const num = Number(raw)
+    const ms = num > 1e11 ? num : num * 1000
+    const d = new Date(ms)
+    if (!Number.isNaN(d.getTime())) return padDate(d)
+  }
+  const parsed = new Date(raw)
+  if (!Number.isNaN(parsed.getTime())) return padDate(parsed)
+  return fallback
+}
+
+function pad(n: string | number): string {
+  return String(n).padStart(2, '0')
+}
+
+function padDate(d: Date): string {
+  const y = d.getFullYear()
+  const mo = pad(d.getMonth() + 1)
+  const day = pad(d.getDate())
+  const h = pad(d.getHours())
+  const mi = pad(d.getMinutes())
+  const s = pad(d.getSeconds())
+  return `${y}-${mo}-${day} ${h}:${mi}:${s}`
+}