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/build_minimp3.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+# minimp3 — header-only (minimp3.h + minimp3_ex.h)。许可 CC0 / MIT。v1 推荐的 MP3 解码器。
+. ./libs_common.sh
+D="$OUT/minimp3/mipsel"; mkdir -p "$D"
+cat > "$D/minimp3_impl.c" <<'C'
+#define MINIMP3_IMPLEMENTATION
+#include "minimp3_ex.h"
+// 拉入 mp3dec_ex_open/read；minimp3.h 由 minimp3_ex.h 内部包含
+C
+$CC_MIPS -Os -I"$VENDOR/minimp3" -fno-stack-protector -ffunction-sections -fdata-sections -c "$D/minimp3_impl.c" -o "$D/minimp3_ex.o" || exit 1
+$AR_MIPS rcs "$D/libminimp3_ex.a" "$D/minimp3_ex.o"
+echo "minimp3 (mipsel, mp3dec_ex):"
+measure_archive "$D/libminimp3_ex.a"