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

server/utils/transcode.test.ts

@@ -0,0 +1,86 @@
+import { describe, expect, it } from 'vitest'
+import {
+  DEFAULT_TRANSCODE_CONCURRENCY,
+  DEFAULT_TRANSCODE_PRESET,
+  DEFAULT_TRANSCODE_THREADS,
+  getTranscodeConcurrency,
+  getTranscodeSettings,
+  hlsPlaylistKey,
+  parseTranscodePreset,
+  setTranscodeSettings,
+  thumbKeyFor
+} from './transcode'
+import { isVideoSidecarKey, mediaTypeForKey } from './image-key'
+
+describe('hlsPlaylistKey', () => {
+  it('uses the video key without extension as the hls directory', () => {
+    expect(hlsPlaylistKey('videos/2026/10/abc123.mp4'))
+      .toBe('videos/2026/10/abc123/index.m3u8')
+    expect(hlsPlaylistKey('videos/abc123.mkv'))
+      .toBe('videos/abc123/index.m3u8')
+  })
+})
+
+describe('isVideoSidecarKey', () => {
+  it('detects playlists, segments and thumbnails', () => {
+    expect(isVideoSidecarKey('videos/2026/10/abc/index.m3u8')).toBe(true)
+    expect(isVideoSidecarKey('videos/2026/10/abc/seg000.ts')).toBe(true)
+    expect(isVideoSidecarKey('videos/2026/10/abc.webp')).toBe(true)
+  })
+
+  it('leaves the original video and other media out', () => {
+    expect(isVideoSidecarKey('videos/2026/10/abc.mp4')).toBe(false)
+    expect(isVideoSidecarKey('files/2026/10/abc.pdf')).toBe(false)
+    expect(isVideoSidecarKey('images/2026/10/abc.webp')).toBe(false)
+  })
+
+  it('builds thumbnail keys next to the video', () => {
+    expect(thumbKeyFor('videos/2026/10/abc.mp4')).toBe('videos/2026/10/abc.webp')
+  })
+})
+
+describe('mediaTypeForKey', () => {
+  it('maps folders to media types', () => {
+    expect(mediaTypeForKey('images/2026/10/a.webp')).toBe('image')
+    expect(mediaTypeForKey('videos/2026/10/a.mp4')).toBe('video')
+    expect(mediaTypeForKey('files/2026/10/a.pdf')).toBe('file')
+  })
+})
+
+describe('transcode settings', () => {
+  it('defaults to one concurrent job with one thread', () => {
+    expect(DEFAULT_TRANSCODE_CONCURRENCY).toBe(1)
+    expect(DEFAULT_TRANSCODE_THREADS).toBe(1)
+    expect(getTranscodeSettings()).toEqual({
+      concurrency: 1,
+      threads: 1,
+      preset: 'veryfast',
+      bitratePercent: 80
+    })
+  })
+
+  it('round-trips stored values', () => {
+    setTranscodeSettings({ concurrency: 3, threads: 2 })
+    expect(getTranscodeSettings()).toEqual({
+      concurrency: 3,
+      threads: 2,
+      preset: 'veryfast',
+      bitratePercent: 80
+    })
+  })
+
+  it('falls back to the default when the stored value is out of range', () => {
+    setTranscodeSettings({ concurrency: 99 })
+    expect(getTranscodeConcurrency()).toBe(DEFAULT_TRANSCODE_CONCURRENCY)
+
+    setTranscodeSettings({ concurrency: 1, threads: 1 })
+  })
+
+  it('stores the quality preset and rejects unknown ones', () => {
+    setTranscodeSettings({ preset: 'slow' })
+    expect(getTranscodeSettings().preset).toBe('slow')
+
+    expect(parseTranscodePreset('nope')).toBeNull()
+    setTranscodeSettings({ preset: DEFAULT_TRANSCODE_PRESET })
+  })
+})