ncm: FLAC 解码落地(dr_flac 0.13.4 单头入库) + 缓存键=歌曲ID+音质档位

- 解码分发 decoder.c：magic(fLaC→dr_flac / 其它→minimp3)；flac ≤16bit→S16、
  >16bit→S32 满幅送 audiod(AUDIO_FMT_S32)，rate/ch/bits 按实际流，零 SRC 零裁剪
- song_url_auto 接受 flac（type 权威/url 扩展名兜底），降级语义不变；flac 下载限幅 1GB
- 缓存键 song_<id>_<level>.<ext>：同歌同档命中不重下，换档新条目旧档留 LRU；
  ext 前导点正名(修双点名)，lookup 回退历史双点名+旧无档键温和兼容
- audio_out S32 通路（AUDIOD/ALSA/WAV）+ 流死重开按 bits 还原格式
- 验证(0 真实请求)：44.1k/16 与 96k/24 自制样本宿主+qemu 帧数/时长精确、
  逐样本零误差；mp3 回归逐帧一致；player_flow_sim P1-P6(新 P6 档位键/flac ext)、
  cache_evict/cover/pagination/window/audiod_chain sim 全 PASS；mipsel 0 warning
- REPORT §19 / VENDOR_NOTES dr_flac 条目；未部署真机（留主会话）

patch_v2/ncm_app/build_ncm_host.sh

@@ -14,7 +14,7 @@ MBED="$OUT/mbedtls/host"
 
 INC="-I. -I../sdk -I../meow_launcherd -Icore \
      -I$SDK_DIR -I$ROOT/patch_v2/meow_launcherd \
-     -Ivendor/mbedtls/include -Ivendor/jsmn -Ivendor/qrcodegen/c -Ivendor/minimp3"
+     -Ivendor/mbedtls/include -Ivendor/jsmn -Ivendor/qrcodegen/c -Ivendor/minimp3 -Ivendor/dr_flac"
 
 echo "==> host SDK objects"
 SDK_SRC="meow_ui_gfx meow_ui_sys meow_ui_theme meow_ui_vol meow_ui_log meow_ui_widget \
@@ -33,11 +33,13 @@ APP_SRC="app/ui/login.c app/ui/home.c app/ui/playlist.c app/ui/player.c \
          app/ui/settings.c app/ui/search.c app/ui/ncm_colors.c app/ui/chrome.c \
          app/logic/appstate.c app/logic/lyric.c app/logic/songmeta.c \
          app/logic/cover.c app/play/player_manager.c app/play/audio_out.c \
-         app/play/ipc_media.c app/play/minimp3_impl.c"
+         app/play/ipc_media.c app/play/decoder.c app/play/minimp3_impl.c"
 for f in $APP_SRC; do
   b=$(basename "$f" .c)
   $CC_HOST -O2 -c -DMEOW_UI_HOST_TEST -DJSMN_HEADER $INC "$f" -o "$OUT/host/$b.o" || { echo "app $f FAILED"; exit 1; }
 done
+# dr_flac 实现 TU：vendor 豁免告警（同 minimp3 口径），放 strict 循环外
+$CC_HOST -O2 -c -Ivendor/dr_flac app/play/dr_flac_impl.c -o "$OUT/host/dr_flac_impl.o" || { echo "dr_flac_impl FAILED"; exit 1; }
 $CC_HOST -O2 -c -DMEOW_UI_HOST_TEST -DJSMN_HEADER $INC app/test/test_ncm_app.c -o "$OUT/host/app_test.o" || exit 1
 
 echo "==> link ncm_host"