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

i18n/locales/en.json

@@ -24,6 +24,8 @@
   "nav": {
     "api": "API",
     "gallery": "Gallery",
+    "videoLibrary": "Video library",
+    "fileLibrary": "File library",
     "stats": "Stats",
     "logs": "Activity log",
     "settings": "Settings",
@@ -298,6 +300,23 @@
     "qualityMedium": "Medium quality",
     "qualityLow": "Lossy",
     "convenience": "Convenience",
+    "videoProcessing": "Video processing",
+    "transcodeToHls": "Transcode to m3u8",
+    "transcodeToHlsHint": "Segment into HLS, uses extra CPU.",
+    "concurrentHint": "at a time",
+    "threadsHint": "per job",
+    "transcodeConcurrency": "Concurrent transcodes",
+    "transcodeThreads": "CPU threads",
+    "unitCount": "",
+    "transcodeQuality": "Quality",
+    "presetCopy": "Remux",
+    "presetSpeed": "Speed",
+    "presetBalanced": "Balanced",
+    "presetQuality": "Quality",
+    "presetCompress": "Compress",
+    "compressBitrate": "Target bitrate",
+    "transcodeLoadFailed": "Failed to load transcode settings",
+    "transcodeSaveFailed": "Failed to save transcode settings",
     "autoCopy": "Copy link after upload",
     "autoCopyHint": "Copy to clipboard in the selected format"
   },
@@ -356,6 +375,12 @@
     "refererUnrestricted": "Unrestricted",
     "loginVerification": "Login verification",
     "loginVerificationHint": "Human verification for login and registration (choose one)",
+    "fileBed": "File bed",
+    "fileBedHint": "Access mode for file download links. Takes effect immediately.",
+    "fileBedPublic": "Public",
+    "fileBedPublicHint": "Anyone with the link can download. Best for sharing.",
+    "fileBedToken": "Token required",
+    "fileBedTokenHint": "Downloads must carry a token (append ?token= to the link). Best for private files.",
     "loginVerificationSlider": "Local slider",
     "loginVerificationSliderHint": "Built-in slider puzzle; no third-party service",
     "loginVerificationTurnstile": "Cloudflare Turnstile",
@@ -816,6 +841,8 @@
     "storageBackend": "Storage: {name}"
   },
   "delete": {
+    "confirmDescVideo": "Delete the selected {count} video(s)? This cannot be undone.",
+    "confirmDescFile": "Delete the selected {count} file(s)? This cannot be undone.",
     "confirmTitle": "Confirm delete",
     "confirmDesc": "Delete {count} selected image(s)? This cannot be undone.",
     "confirm": "Delete"
@@ -967,6 +994,76 @@
       }
     }
   },
+  "files": {
+    "maxFiles": "Up to {n} files per upload",
+    "uploadSuccess": "Uploaded {n} file(s)",
+    "uploadFailed": "Upload failed, please try again",
+    "loadFailed": "Failed to load files",
+    "copyLink": "Copy link",
+    "download": "Download",
+    "deleted": "Deleted",
+    "deleteFailed": "Delete failed"
+  },
+  "host": {
+    "video": "Video",
+    "file": "File",
+    "imageFull": "Personal lightweight image host",
+    "videoFull": "Personal lightweight video host",
+    "fileFull": "Personal lightweight file host"
+  },
+  "library": {
+    "play": "Play",
+    "copyVideoLink": "Copy video link",
+    "copyThumbLink": "Copy thumbnail link",
+    "selectedCount": "{n} selected",
+    "selectFirst": "Select videos first",
+    "clearSelection": "Clear",
+    "reset": "Reset",
+    "batchDelete": "Delete",
+    "deleted": "Deleted {n} video(s)",
+    "fileDeleted": "Deleted {n} file(s)",
+    "deletePartialFail": "{n} video(s) failed to delete",
+    "statsToday": "Uploaded today",
+    "statsMonth": "This month",
+    "statsTotal": "Videos",
+    "statsBytes": "Total size",
+    "statsUsage": "Storage usage",
+    "statsSource": "Upload source",
+    "statsTotalHintVideo": "Total videos",
+    "statsTotalHintFile": "Total files",
+    "statsTotalHintImage": "Total images",
+    "statsVsYesterday": "vs yesterday {value}",
+    "statsVsLastMonth": "vs last month {value}",
+    "transcodePending": "Queued",
+    "transcoding": "Transcoding",
+    "transcodeFailed": "Transcode failed",
+    "searchPlaceholder": "Search file name",
+    "searchEmpty": "Nothing matched",
+    "clearSearch": "Clear search",
+    "file": {
+      "title": "File bed",
+      "subtitle": "Manage uploaded files, copy links or download",
+      "uploadTitle": "Drop files here to upload",
+      "uploadHint": "or click to choose files, up to 10 at a time",
+      "uploadFormats": "Any type allowed (HTML / HTM / SVG blocked), up to 100MB per file",
+      "empty": "No files yet — upload one to get started"
+    },
+    "video": {
+      "title": "Videos",
+      "subtitle": "Manage uploaded videos, copy links or download",
+      "previewTitle": "Video details",
+      "previewSubtitle": "View video info and links",
+      "previewTranscode": "Transcode",
+      "previewThumbLink": "Thumbnail link",
+      "previewKey": "Video path",
+      "transcodeNone": "Not transcoded",
+      "transcodeDone": "Done (m3u8)",
+      "uploadTitle": "Drop videos here to upload",
+      "uploadHint": "or click to choose video files, up to 10 at a time",
+      "uploadFormats": "MP4 / WebM / MOV / MKV and more, up to 100MB per file",
+      "empty": "No videos yet — upload one to get started"
+    }
+  },
   "userSettings": {
     "loadFailed": "Failed to load settings",
     "saveFailed": "Failed to save settings"