feat(ncm): 网易云技术栈预研+构建验证 (agent-200) — 选型: mbedtls3.6.2裁剪(TLS+AES+MD5+RSA raw+Base64,~388KB)/jsmn(2.2KB)/qrcodegen(10.8KB)/minimp3(37.4KB), 合计~438KB; HTTPS unikey 全链路宿主+qemu-mipsel 实测通过; RSA raw 与 Python pow 逐字节一致; MP3 解码非瓶颈

vendor源码+out产物不入库(126MB, gitignore; 版本/许可/裁剪见 VENDOR_NOTES.md, build_*.sh 可复现)

patch_v2/ncm_app/bench/bench_minimp3.c

@@ -0,0 +1,19 @@
+#define MINIMP3_IMPLEMENTATION
+#include "minimp3_ex.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+static double now(){ struct timespec ts; clock_gettime(CLOCK_MONOTONIC,&ts); return ts.tv_sec+ts.tv_nsec*1e-9; }
+int main(int argc,char**argv){
+  if(argc<2){fprintf(stderr,"usage: %s file.mp3\n",argv[0]);return 1;}
+  mp3dec_t dec; mp3dec_init(&dec);
+  mp3dec_file_info_t info; memset(&info,0,sizeof info);
+  double t0=now(); int r=mp3dec_load(&dec,argv[1],&info,NULL,NULL); double t1=now();
+  if(r){fprintf(stderr,"decode fail %d\n",r);return 1;}
+  long long frames=info.samples/info.channels;
+  printf("rate=%d ch=%d total_pcm_frames=%lld\n",info.hz,info.channels,frames);
+  printf("wall=%.3f s  throughput=%.1f xRT  (%.1f frames/s)\n",(t1-t0),
+    (double)frames/info.hz/(t1-t0),(double)frames/(t1-t0));
+  free(info.buffer); return 0;
+}