feat(files): wide file manager layout and basic previews (FM-2)

- Files page uses a wide layout (route handle layout:"wide"): no max width,
  full-height directory tree docked next to the sidebar, resizable
  (200-520px, remembered, double-click resets) and collapsible; mobile keeps
  the tree in a drawer.
- GET /files/preview (admin console session only, same path guards as
  download): text/NFO with encoding detection (BOM/UTF-16/UTF-8/GB18030/Big5),
  subtitles first 200 cues (SRT/VTT/ASS/SSA, PGS timings), .torrent file
  list/trackers (passkey masked)/infohash, image dimensions. Reads at most
  1 MiB of text; .torrent capped at 4 MiB.
- Download also allows text files, .torrent and avif/gif.
- Research notes in docs/design/file-preview-research.md.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/server/src/modules/file-manager/download.ts

@@ -4,6 +4,7 @@ import type { Principal } from "../../http/auth.ts";
 import { FilesError, type FmDeps, isAdminSession, recheck, resolveIn } from "./common.ts";
 import { audit } from "./ledger.ts";
 import { kindOfName } from "./list.ts";
+import { previewKindOf } from "./preview-parse.ts";
 
 // GET /files/download(W5-A2):仅管理员会话;只下载 NFO/字幕/图片小文件(视频不经浏览器,规格 §1 边界);
 // 路径守卫同其它接口(realpath 在根内、符号链接目标也须在根内,打开前再复核一次);
@@ -19,6 +20,7 @@ const MIME: Record<string, string> = {
   webp: "image/webp",
   bmp: "image/bmp",
   avif: "image/avif",
+  torrent: "application/x-bittorrent",
   nfo: "text/plain; charset=utf-8",
   xml: "text/plain; charset=utf-8",
   srt: "text/plain; charset=utf-8",
@@ -48,7 +50,10 @@ export async function downloadFile(
   if (r.rel === "" || r.lst?.isDirectory()) throw new FilesError("bad_request", "只能下载文件，不能下载目录");
   const name = basename(r.abs);
   const kind = kindOfName(name);
-  if (!ALLOWED.has(kind)) throw new FilesError("forbidden", `只能下载 NFO、字幕和图片，此文件类型为 ${kind}`);
+  // FM-2:可预览的文本类(txt/log/md/json…)、.torrent、avif/gif 也允许下载
+  const pk = previewKindOf(name);
+  if (!ALLOWED.has(kind) && !pk)
+    throw new FilesError("forbidden", `只能下载 NFO、字幕、图片、文本和 .torrent，此文件类型为 ${kind}`);
   const real = await recheck(r.abs, r.rootReal);
   const file = await Deno.open(real, { read: true });
   let size: number;
@@ -67,7 +72,7 @@ export async function downloadFile(
   }
   const ext = extname(name).replace(/^\./, "").toLowerCase();
   // SVG 可带脚本:不内联、不给 image/svg+xml
-  const inline = q.inline && kind === "image" && ext !== "svg";
+  const inline = q.inline && (kind === "image" || pk === "image") && ext !== "svg";
   await audit(d, principal, "download", { root: q.root, path: r.rel, size, inline });
   return new Response(file.readable, {
     status: 200,