v1.4.3: 관리자 UI·홈·미디어 개선

- 관리자 라이트 테마 격리, 대시보드 활성 링크, 로그인 우측 정렬
- 대시보드 통계 추이 차트·툴팁, 홈 Latest/Featured 보정
- 미디어 종류·미사용 필터, 비디오 프레임 썸네일
- NAS 운영 업데이트 절차 문서 추가

components/admin/AdminMediaVideoThumbnail.vue

@@ -0,0 +1,107 @@
+<script setup>
+const props = defineProps({
+  /** 비디오 파일 URL */
+  src: {
+    type: String,
+    required: true
+  },
+  /** 접근성 대체 텍스트 */
+  alt: {
+    type: String,
+    default: '비디오 썸네일'
+  }
+})
+
+const videoRef = ref(null)
+const canvasRef = ref(null)
+const thumbnailUrl = ref('')
+const failed = ref(false)
+
+/**
+ * 비디오 프레임을 캔버스 이미지로 변환한다.
+ * @returns {void}
+ */
+const captureVideoFrame = () => {
+  const video = videoRef.value
+  const canvas = canvasRef.value
+
+  if (!video || !canvas || !video.videoWidth || !video.videoHeight) {
+    failed.value = true
+    return
+  }
+
+  canvas.width = video.videoWidth
+  canvas.height = video.videoHeight
+
+  const context = canvas.getContext('2d')
+  if (!context) {
+    failed.value = true
+    return
+  }
+
+  try {
+    context.drawImage(video, 0, 0, canvas.width, canvas.height)
+    thumbnailUrl.value = canvas.toDataURL('image/jpeg', 0.78)
+  } catch {
+    failed.value = true
+  }
+}
+
+/**
+ * 메타데이터 로드 후 초반 프레임으로 이동한다.
+ * @returns {void}
+ */
+const seekPreviewFrame = () => {
+  const video = videoRef.value
+  if (!video) {
+    failed.value = true
+    return
+  }
+
+  const duration = Number.isFinite(video.duration) ? video.duration : 0
+  const targetTime = duration > 1 ? Math.min(1, duration * 0.1) : 0
+
+  try {
+    video.currentTime = targetTime
+  } catch {
+    captureVideoFrame()
+  }
+}
+</script>
+
+<template>
+  <span class="admin-media-video-thumbnail relative block aspect-square w-full overflow-hidden bg-surface">
+    <img
+      v-if="thumbnailUrl"
+      class="admin-media-video-thumbnail__image h-full w-full object-cover"
+      :src="thumbnailUrl"
+      :alt="alt"
+      loading="lazy"
+    >
+    <span
+      v-else
+      class="admin-media-video-thumbnail__fallback flex h-full w-full items-center justify-center text-xs font-bold uppercase tracking-[0.18em] text-muted"
+    >
+      video
+    </span>
+    <span class="admin-media-video-thumbnail__badge absolute bottom-1.5 left-1.5 rounded bg-black/70 px-1.5 py-0.5 text-[10px] font-semibold uppercase tracking-[0.12em] text-white">
+      video
+    </span>
+    <video
+      ref="videoRef"
+      class="hidden"
+      :src="src"
+      muted
+      playsinline
+      preload="metadata"
+      crossorigin="anonymous"
+      @loadedmetadata="seekPreviewFrame"
+      @seeked="captureVideoFrame"
+      @error="failed = true"
+    />
+    <canvas ref="canvasRef" class="hidden" aria-hidden="true" />
+    <span v-if="failed && !thumbnailUrl" class="sr-only">
+      {{ alt }}
+    </span>
+  </span>
+</template>