Initial commit: Add project files

frontend/src/shared/status/DataFreshnessBadge.vue

@@ -0,0 +1,17 @@
+<script setup lang="ts">
+import { computed } from 'vue'
+
+const props = defineProps<{
+  asOf: string
+  staleAfterMinutes: number
+}>()
+
+const ageMinutes = computed(() => Math.max(0, (Date.now() - new Date(props.asOf).getTime()) / 60_000))
+const stale = computed(() => ageMinutes.value > props.staleAfterMinutes)
+</script>
+
+<template>
+  <span :aria-label="stale ? '데이터 지연' : '데이터 최신'" :data-status="stale ? 'stale' : 'fresh'">
+    {{ stale ? 'STALE' : 'FRESH' }} · {{ new Date(props.asOf).toLocaleString() }}
+  </span>
+</template>