feat(local): 支持上传并播放本地视频文件，只保留音轨 (#149)

本地上传此前只接受音频。想放一段本地 mp4/mov/avi 里的音乐，四道关卡
挡着（前两道在服务端，后两道在浏览器端）：

1. src/music/local.ts 的 AUDIO_EXTENSIONS 只列了 12 种音频后缀；
2. src/web/api/music.ts 里 express.raw 的 type 只匹配 audio/*、
   video/webm、application/octet-stream —— 浏览器给 .mp4 打的
   Content-Type 是 video/mp4，请求体压根不会被解析，处理函数看到
   req.body === undefined，回 400「raw audio body is required」；
3. Search.vue 的 accept 属性让文件选择框把视频文件置灰；
4. isAudioFile() 把拖进来的视频文件静默丢掉。

ffmpeg 层不是瓶颈：s16le 输出格式不接受视频，ffmpeg 的自动选流本来
就只挑音轨。实测 mp4/mov/avi/mkv/flv/wmv/ts/m4v/mpg 九种容器用现有
参数全部正常出声，多音轨、带字幕、带 timecode 的也一样，所以
buildFfmpegArgs 一个字没动。

## 改动

- **打通四道关卡**：新增 VIDEO_EXTENSIONS（mp4/mov/avi/mkv/flv/wmv/
  m4v/mpg/mpeg/3gp/ts/m2ts/ogv），express.raw 收 video/*，前端 accept
  与过滤函数同步放宽。
- **上传时抽取音轨**（extractAudioTrack）：视频落盘后用
  `-vn -sn -dn -map 0:a:0 -c:a copy` 把音轨原样搬进 Matroska 音频容器
  （.mka）再删掉原视频。`-c:a copy` 不重编码，无损、快，且 Matroska
  几乎收所有音频编码，不用维护「编码→后缀」对照表。实测 720p 素材
  落盘体积降到原文件的 14%，这对 5 GiB 的上传目录配额很关键——否则
  十来个视频就把配额占满了。抽取失败（冷门编码、超时）则保留原容器
  继续播，只是占地方，绝不会因此上传失败。
- **拒绝没有音轨的视频**：上传时探测，直接回「这个视频里没有音轨，
  无法播放」，而不是等到播放时静默跳过。只在 ffmpeg 确实打开了容器
  （打印了 `Input #0,`）时才拒绝——认不出的字节一律放行，截断的 mp3
  一直是这个行为，不能因为这次改动开始被拒。
- **上限从 200mb 提到 500mb**，并把超限响应从 Express 默认的 HTML
  错误页（带堆栈和服务器绝对路径）换成和本路由一致的 JSON；前端也加
  了同样的预检，不再传完几百兆才被拒。
- **上传进度**：视频比音频大得多，原来那句静止的「正在上传 N 个文件」
  看着像卡死，现在按文件显示百分比，传完切到「服务端处理中」。

## 验证

- 全量 `npx vitest run`：136 个文件 / 2070 项，新增 24 项。
- 新增测试用 ffmpeg 现造真实容器跑端到端：mp4 上传后时长正确、原
  容器已删、剩下的 .mka 能被播放链路解码出 PCM；avi/mkv/flv 同样；
  无音轨视频被拒且不留残留文件；纯音频上传字节数不变、不被重封装。
- 变异测试（逐个改回旧实现，确认新测试真的会红）：后缀白名单 4 项失败、
  express.raw 的 type 5 项失败、抽取音轨 2 项失败、无音轨拒绝 2 项失败。
- `npx tsc --noEmit` 与 `npx vue-tsc --noEmit` 均 exit 0。

Reported-by: @LadenceE
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/web/api/music.test.ts

@@ -14,7 +14,7 @@ import { createSessionStore } from "../../data/sessions.js";
 import { createPermissionStore } from "../../data/permissions.js";
 import { createRequireAuth } from "../middleware/requireAuth.js";
 import { SESSION_COOKIE_NAME } from "../auth/validateSession.js";
-import { createMusicRouter } from "./music.js";
+import { createMusicRouter, createLocalUploadBody } from "./music.js";
 
 const empty: SearchResult = { songs: [], albums: [], playlists: [] };
 
@@ -295,3 +295,146 @@ describe("music router POST /quality — persistence (#125)", () => {
     expect(config.audioQuality.netease).toBe("lossless");
   });
 });
+
+// #149: video containers must survive the transport layer. Before this the
+// express.raw type filter only matched audio/*, video/webm and
+// application/octet-stream, so a browser-sent video/mp4 body was never parsed
+// and the handler answered 400 "raw audio body is required".
+describe("music router POST /local/upload — content types and size cap (#149)", () => {
+  let app: express.Express;
+  let botDb: BotDatabase;
+  let cookie: string;
+  let uploadAudio: ReturnType<typeof vi.fn>;
+
+  beforeEach(async () => {
+    botDb = createDatabase(":memory:");
+    const users = createUserStore(botDb.db);
+    const sessions = createSessionStore(botDb.db);
+    const admin = await users.createUser("admin", "pw-admin", "admin");
+    cookie = `${SESSION_COOKIE_NAME}=${sessions.createSession(admin.id).token}`;
+
+    uploadAudio = vi.fn(async (input: { originalName: string }) => ({
+      id: "local-1", name: input.originalName, artist: "本地上传", album: "本地音乐",
+      duration: 1, coverUrl: "", platform: "local",
+    }));
+    const local = { platform: "local", search: vi.fn().mockResolvedValue(empty), uploadAudio } as unknown as MusicProvider;
+
+    app = express();
+    app.use(express.json());
+    app.use(cookieParser());
+    app.use("/api", createRequireAuth(sessions, createPermissionStore(botDb.db), () => getDefaultConfig().guestMode));
+    app.use("/api/music", createMusicRouter(
+      fakeProvider("netease"), fakeProvider("qq"), fakeProvider("bilibili"),
+      pino({ level: "silent" }), local, getDefaultConfig(),
+    ));
+  });
+
+  afterEach(() => botDb.close());
+
+  const post = (contentType: string, body: Buffer, name = "clip.mp4") =>
+    request(app)
+      .post("/api/music/local/upload")
+      .set("Cookie", cookie)
+      .set("Content-Type", contentType)
+      .set("X-Filename", encodeURIComponent(name))
+      .send(body);
+
+  it("accepts the video MIME types browsers actually send", async () => {
+    // These are what Chrome/Firefox put on a File for .mp4/.mov/.avi/.mkv.
+    for (const ct of ["video/mp4", "video/quicktime", "video/x-msvideo", "video/x-matroska", "video/webm"]) {
+      uploadAudio.mockClear();
+      const res = await post(ct, Buffer.from("fake video bytes"));
+      expect(res.status, `content-type ${ct}`).toBe(200);
+      expect(uploadAudio).toHaveBeenCalledOnce();
+      expect(res.body.song.platform).toBe("local");
+    }
+  });
+
+  it("still accepts audio and octet-stream bodies", async () => {
+    for (const ct of ["audio/mpeg", "audio/flac", "application/octet-stream"]) {
+      uploadAudio.mockClear();
+      const res = await post(ct, Buffer.from("fake audio"), "tune.mp3");
+      expect(res.status, `content-type ${ct}`).toBe(200);
+      expect(uploadAudio).toHaveBeenCalledOnce();
+    }
+  });
+
+  it("passes the decoded filename and the content type through to the provider", async () => {
+    await post("video/mp4", Buffer.from("bytes"), "我的 视频.mp4");
+    expect(uploadAudio).toHaveBeenCalledWith(
+      expect.objectContaining({ originalName: "我的 视频.mp4", mimeType: "video/mp4" }),
+    );
+  });
+
+  it("surfaces a provider rejection as a 400 with its message", async () => {
+    uploadAudio.mockRejectedValueOnce(new Error("这个视频里没有音轨，无法播放"));
+    const res = await post("video/mp4", Buffer.from("bytes"));
+    expect(res.status).toBe(400);
+    expect(res.body.error).toBe("这个视频里没有音轨，无法播放");
+  });
+
+  it("requires authentication", async () => {
+    const res = await request(app)
+      .post("/api/music/local/upload")
+      .set("Content-Type", "video/mp4")
+      .send(Buffer.from("bytes"));
+    expect(res.status).toBe(401);
+  });
+
+  it("rejects an oversize body as JSON, not an HTML stack trace", async () => {
+    // Same middleware the route mounts, built with a small limit so the test
+    // does not have to allocate half a gigabyte to reach the cap.
+    const tiny = express();
+    const reached = vi.fn();
+    tiny.post("/u", createLocalUploadBody("1kb"), (_req, res) => { reached(); res.json({ ok: true }); });
+
+    const res = await request(tiny)
+      .post("/u")
+      .set("Content-Type", "video/mp4")
+      .send(Buffer.alloc(4096, 1));
+
+    expect(res.status).toBe(413);
+    expect(res.headers["content-type"]).toMatch(/application\/json/);
+    expect(res.body.error).toContain("文件太大");
+    // The HTML default handler leaked absolute server paths and a stack.
+    expect(res.text).not.toMatch(/node_modules|<\/pre>|at read/);
+    expect(reached).not.toHaveBeenCalled();
+  });
+
+  it("lets a body under the cap through the same middleware", async () => {
+    const tiny = express();
+    tiny.post("/u", createLocalUploadBody("1kb"), (req, res) => {
+      res.json({ bytes: (req.body as Buffer).length });
+    });
+    const res = await request(tiny)
+      .post("/u")
+      .set("Content-Type", "video/mp4")
+      .send(Buffer.alloc(512, 1));
+    expect(res.status).toBe(200);
+    expect(res.body.bytes).toBe(512);
+  });
+
+  it("rejects local uploads when the feature is switched off", async () => {
+    const off = getDefaultConfig();
+    off.localAudioEnabled = false;
+    const users = createUserStore(botDb.db);
+    const sessions = createSessionStore(botDb.db);
+    const a2 = await users.createUser("admin2", "pw-admin2", "admin");
+    const c2 = `${SESSION_COOKIE_NAME}=${sessions.createSession(a2.id).token}`;
+    const app2 = express();
+    app2.use(cookieParser());
+    app2.use("/api", createRequireAuth(sessions, createPermissionStore(botDb.db), () => getDefaultConfig().guestMode));
+    app2.use("/api/music", createMusicRouter(
+      fakeProvider("netease"), fakeProvider("qq"), fakeProvider("bilibili"),
+      pino({ level: "silent" }),
+      { platform: "local", search: vi.fn(), uploadAudio } as unknown as MusicProvider, off,
+    ));
+    const res = await request(app2)
+      .post("/api/music/local/upload")
+      .set("Cookie", c2)
+      .set("Content-Type", "video/mp4")
+      .send(Buffer.from("bytes"));
+    expect(res.status).toBe(403);
+    expect(uploadAudio).not.toHaveBeenCalled();
+  });
+});