ncm 三期三批: 歌曲对象瘦身(1324→608B)+滑动窗口(NCM_SONG_WINDOW=256, 取消1000截断支撑任意长度歌单)+播放快照解耦 — agent-251

- core/ncm_api.h: ncm_song_t 瘦身 id24/name128/art96/al96/pic256/dt int32 (1324B→608B)
- appstate.c 滑动窗口: song_ids 全量 trackIds 索引(16384) + songs[256] 窗口感知
  (song_valid 位图/window_base/滑窗 memmove 保留重叠), ensure_range 批网格(100)对齐
  预取, songmeta.c 盘缓存 <cache_dir>/meta/<id>.bin (回滚/二次进入 0 网络请求)
- playlist.c 触底分页退役→视口 ensure(±24 行), 占位行可直点(播放线程 fetch 物化),
  footer 改视口区间/总数
- 播放兼容: g_play.play_song 快照(mu), run_song 起播物化后全链路(下载/歌词/IPC META/
  播放页 UI)读快照——窗口滑出当前播放曲不崩; 边界 song_count→track_ids_count
- 验证(0 真实请求): pagination_sim 全 PASS(5191 无截断/52 批); window_sim 6000 首
  全程下滚 750 步视口全物化/song_detail 恰 60 次/回滚+0 请求/播放 fetch 不滑窗;
  core 宿主+qemu 全 PASS; mipsel -Wall -Wextra 0 warning, bss 2052068→1080900(-47%)
- 未部署真机(设备音频线排查中, 部署留主会话)

patch_v2/ncm_app/build_ncm.sh

@@ -19,7 +19,7 @@ CORE="core/ncm_common.c core/ncm_json.c core/ncm_store.c core/ncm_http.c \
       core/ncm_cache.c core/ncm_ctx.c"
 APP="app/app.c 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/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"