refactor: 架构整固——分层单向化、全量 TypeScript、直接运行

- 移除 bd/mg 两平台及磁盘残留产物；清理 api-test 死脚本、musicSdk/message+options 死模块、infSign vendor
- musicSdk/ 改名 sdk/；src/common、src/auth、src/apis 整体移入 sdk/，依赖方向定为 src → sdk 严格单向
- src/ 手写 JS 全量转 .ts，删除 JS 类型垫片 modules.d.ts；源码 import 统一 .ts 后缀
- Node 原生类型剥离直接运行 .ts（engines >=22.18），取消 tsc 发射产物，tsc 仅类型检查（pnpm typecheck）
- 删除 kwdes 备用实现与 src/index.ts 转发垫片；测试移至 test/smoke-test.ts
- common/request.ts 补显式导出类型；修复 set-cookie 单值形态、ApiError 类字段等隐患

验证：tsc 零错误，smoke-test 41/41

sdk/common/lyricUtils/kg.ts

@@ -0,0 +1,78 @@
+// 酷狗 krc 歌词解码
+
+import zlib from 'node:zlib'
+import { decodeName } from '../utils.ts'
+
+// 基于社区通用的 krc 解析思路
+const enc_key = Buffer.from([0x40, 0x47, 0x61, 0x77, 0x5e, 0x32, 0x74, 0x47, 0x51, 0x36, 0x31, 0x2d, 0xce, 0xd2, 0x6e, 0x69])
+
+const decodeLyric = str => new Promise((resolve, reject) => {
+  if (!str.length) return
+  const buf_str = Buffer.from(str, 'base64').subarray(4)
+  for (let i = 0, len = buf_str.length; i < len; i++) {
+    buf_str[i] = buf_str[i] ^ enc_key[i % 16]
+  }
+  zlib.inflate(buf_str, (err, result) => {
+    if (err) return reject(err)
+    resolve(result.toString())
+  })
+})
+
+const headExp = /^.*\[id:\$\w+\]\n/
+
+const parseLyric = str => {
+  str = str.replace(/\r/g, '')
+  if (headExp.test(str)) str = str.replace(headExp, '')
+  let trans = str.match(/\[language:([\w=\\/+]+)\]/)
+  let lyric
+  let rlyric
+  let tlyric
+  if (trans) {
+    str = str.replace(/\[language:[\w=\\/+]+\]\n/, '')
+    let json = JSON.parse(Buffer.from(trans[1], 'base64').toString())
+    for (const item of json.content) {
+      switch (item.type) {
+        case 0:
+          rlyric = item.lyricContent
+          break
+        case 1:
+          tlyric = item.lyricContent
+          break
+      }
+    }
+  }
+  let i = 0
+  let yrc = str.replace(/\[((\d+),\d+)\].*/g, str => {
+    let result = str.match(/\[((\d+),\d+)\].*/)
+    let time: any = parseInt(result[2])
+    let ms = time % 1000
+    time /= 1000
+    let m = Math.trunc(time / 60).toString().padStart(2, '0')
+    time %= 60
+    let s = Math.trunc(time).toString().padStart(2, '0')
+    time = `${m}:${s}.${ms}`
+    if (rlyric) rlyric[i] = `[${time}]${rlyric[i]?.join('') ?? ''}`
+    if (tlyric) tlyric[i] = `[${time}]${tlyric[i]?.join('') ?? ''}`
+    i++
+    return str.replace(result[1], time)
+  })
+  rlyric = rlyric ? rlyric.join('\n') : ''
+  tlyric = tlyric ? tlyric.join('\n') : ''
+  yrc = yrc.replace(/<(\d+,\d+),\d+>/g, '<$1>')
+  yrc = decodeName(yrc)
+  lyric = yrc.replace(/<\d+,\d+>/g, '')
+  rlyric = decodeName(rlyric)
+  tlyric = decodeName(tlyric)
+  return {
+    lyric,
+    tlyric,
+    rlyric,
+    yrc,
+  }
+}
+
+export const decodeKrc = async data => {
+  return decodeLyric(data).then(parseLyric)
+}
+
+export default { decodeKrc }