feat: 新增视频床与文件床，视频支持 HLS 转码

文件床
- 新增 files/ 存储前缀与 media_type 索引列，图片、视频、文件三类资源独立
- 新增文件上传、列表、删除、批量删除接口，禁止 html/htm/svg
- 支持公开直链与 Token 访问两种模式，后台可切换，直链强制附件下载

视频床
- 新增 videos/ 存储前缀与视频上传接口，单文件上限 500MB
- 接入 ffmpeg 转码队列，并发数与单任务核心数可配，默认串行
- 五档转码质量：直接封装 / 速度 / 平衡 / 质量 / 压缩（压缩档可调码率比例）
- 码率控制避免转码后体积反超源文件，音频跟随源音轨不放大不压缩
- 转码进度实时上报，成功后删除源文件，失败时保留源文件与可用链接
- 上传时自动抽帧生成封面，视频与封面各有独立链接
- 删除视频时中断转码并清理切片、封面与源文件

媒体库
- 图库、视频库、文件库三套独立统计，含趋势、占用与来源分布
- 统一筛选、多选、批量删除、批量标签、网格/列表切换，显示方式按类型分别记忆
- 视频详情对齐图片详情，视频库支持在线播放（hls.js，兼容回退原文件）

修复
- 清理无主的切片、封面与开发期遗留的 ffmpeg 进程
- 源文件按设计删除后，索引不再被启动孤儿清理误删
- 视频统计口径与列表一致，转码中的视频不计入统计
- 转码失败时回收已写入的部分切片，避免残留
- 设置页停用检查更新（与上游版本号已不对应）

其他
- Docker 镜像安装 ffmpeg
- git remote 指向内网仓库

app/components/AppShell.vue

@@ -13,7 +13,9 @@ const mobileUserOpen = ref(false)
 const navItems = computed(() => {
   const items = [
     { label: t('nav.api'), to: '/api', icon: 'i-lucide-code-2' },
-    { label: t('nav.gallery'), to: '/gallery', icon: 'i-lucide-images' }
+    { label: t('nav.gallery'), to: '/gallery', icon: 'i-lucide-images' },
+    { label: t('nav.videoLibrary'), to: '/video-library', icon: 'i-lucide-film' },
+    { label: t('nav.fileLibrary'), to: '/file-library', icon: 'i-lucide-folder-open' }
   ]
   if (isAdmin.value) {
     items.push({ label: t('nav.storage'), to: '/storage', icon: 'i-lucide-hard-drive' })
@@ -22,6 +24,28 @@ const navItems = computed(() => {
   return items
 })
 
+/** 三个上传入口，与顶部 Logo 并列 */
+const hostItems = computed(() => [
+  {
+    label: t('host.video'),
+    to: '/videos',
+    icon: 'i-lucide-film',
+    title: t('host.videoFull')
+  },
+  {
+    label: t('host.file'),
+    to: '/files',
+    icon: 'i-lucide-folder-open',
+    title: t('host.fileFull')
+  }
+])
+
+const mobileNavItems = computed(() => [...hostItems.value, ...navItems.value])
+
+function isHostActive(to: string) {
+  return route.path === to || route.path.startsWith(`${to}/`)
+}
+
 const accountMenuItems = computed<DropdownMenuItem[]>(() => [
   {
     label: t('nav.changePassword'),
@@ -66,34 +90,50 @@ async function handleLogout() {
     <header class="sticky top-0 z-40 border-b border-default bg-default/80 backdrop-blur">
       <div class="mx-auto max-w-7xl px-4 py-2.5 sm:px-6">
         <div class="flex items-center justify-between gap-3">
-          <NuxtLink
-            to="/"
-            :title="t('nav.backToUpload')"
-            class="group flex min-w-0 shrink items-center gap-2.5 transition-opacity hover:opacity-90 sm:gap-3"
-          >
-            <img
-              :src="logoLight"
-              alt="PicHost"
-              class="h-9 w-auto shrink-0 object-contain sm:h-11 dark:hidden"
-              decoding="async"
-              draggable="false"
+          <div class="flex min-w-0 items-center gap-2 sm:gap-3">
+            <NuxtLink
+              to="/"
+              :title="t('host.imageFull')"
+              class="group flex min-w-0 shrink items-center gap-2.5 transition-opacity hover:opacity-90 sm:gap-3"
             >
-            <img
-              :src="logoDark"
-              alt="PicHost"
-              class="hidden h-9 w-auto shrink-0 object-contain sm:h-11 dark:block"
-              decoding="async"
-              draggable="false"
-            >
-            <div class="min-w-0 leading-tight">
-              <p class="text-[15px] font-bold tracking-tight sm:text-base">
-                <span class="text-highlighted">Pic</span><span class="text-primary">Host</span>
-              </p>
-              <p class="mt-0.5 hidden text-[11px] text-muted min-[380px]:block sm:text-xs">
-                {{ t('app.tagline') }}
-              </p>
-            </div>
-          </NuxtLink>
+              <img
+                :src="logoLight"
+                alt="PicHost"
+                class="h-9 w-auto shrink-0 object-contain sm:h-11 dark:hidden"
+                decoding="async"
+                draggable="false"
+              >
+              <img
+                :src="logoDark"
+                alt="PicHost"
+                class="hidden h-9 w-auto shrink-0 object-contain sm:h-11 dark:block"
+                decoding="async"
+                draggable="false"
+              >
+              <div class="min-w-0 leading-tight">
+                <p class="text-[15px] font-bold tracking-tight sm:text-base">
+                  <span class="text-highlighted">Pic</span><span class="text-primary">Host</span>
+                </p>
+                <p class="mt-0.5 hidden text-[11px] text-muted min-[380px]:block sm:text-xs">
+                  {{ t('app.tagline') }}
+                </p>
+              </div>
+            </NuxtLink>
+
+            <nav class="hidden items-center gap-1 sm:flex">
+              <UButton
+                v-for="item in hostItems"
+                :key="item.to"
+                :to="item.to"
+                :icon="item.icon"
+                :label="item.label"
+                :title="item.title"
+                size="sm"
+                :variant="isHostActive(item.to) ? 'soft' : 'ghost'"
+                :color="isHostActive(item.to) ? 'primary' : 'neutral'"
+              />
+            </nav>
+          </div>
 
           <ClientOnly>
             <div class="flex shrink-0 items-center gap-0.5 sm:gap-1">
@@ -124,7 +164,7 @@ async function handleLogout() {
                 />
                 <MobileNavMenu
                   v-model:open="mobileNavOpen"
-                  :items="navItems"
+                  :items="mobileNavItems"
                 />
               </div>