feat: 下载沿用曲库已有的歌手 / 专辑文件夹写法

歌手或专辑文件夹名与曲库已有文件夹只差空格、大小写、全半角时（如
「G.E.M.邓紫棋」与「G.E.M. 邓紫棋」），放进已有文件夹，并把歌手、
专辑歌手标签统一成该写法，避免同一歌手被拆成两个目录 / 两个艺人。

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/src/core/pipeline.ts

@@ -3,7 +3,7 @@
 import fs from 'node:fs';
 import path from 'node:path';
 import type { Layout } from '../config.ts';
-import { resolveTarget } from './layout.ts';
+import { applyArtistAlias, resolveTarget } from './layout.ts';
 import { mergeLrc, parseCredits } from './lyrics.ts';
 import { downloadToFile, fetchBuffer, type Progress } from './net/http.ts';
 import type { QualityKey } from './quality.ts';
@@ -100,7 +100,7 @@ async function downloadOnce(provider: MusicProvider, id: string, opts: DownloadO
   reporter?.stage?.('metadata', '获取元数据');
   const meta = await provider.getTrackMeta(id).catch(() => null);
   const name = audio.name || meta?.name || id;
-  const artists = audio.artists || meta?.artists || '未知歌手';
+  let artists = audio.artists || meta?.artists || '未知歌手';
   const album = audio.album || meta?.album || '';
 
   const target = resolveTarget(ctx.musicDir, opts.layout, {
@@ -111,6 +111,15 @@ async function downloadOnce(provider: MusicProvider, id: string, opts: DownloadO
     trackNo: meta?.trackNo,
     trackTotal: meta?.trackTotal,
   });
+  // 沿用了曲库已有的歌手文件夹名（如「G.E.M. 邓紫棋」）时，标签里的歌手名也统一成该写法
+  if (target.artistAlias) {
+    artists = applyArtistAlias(artists, target.artistAlias)!;
+    if (meta) {
+      meta.albumArtist = applyArtistAlias(meta.albumArtist, target.artistAlias);
+      meta.albumArtistPrimary = target.artistAlias.to;
+    }
+    reporter?.log?.('info', `歌手名统一为曲库已有写法：${target.artistAlias.to}`);
+  }
   await fs.promises.mkdir(target.dir, { recursive: true });
   const dest = path.join(target.dir, `${target.baseName}.${audio.ext}`);