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/app/play/audio_out.c

@@ -62,7 +62,7 @@ static void pivset(struct snd_interval *iv, unsigned val)
 }
 static int alsa_open(int rate, int ch, int bits)
 {
-    if (bits != 16) return -1;
+    if (bits != 16 && bits != 32) return -1;   /* §19：S16 + S32（flac >16bit 满幅） */
     int fd = open("/dev/snd/pcmC0D0p", O_RDWR);
     if (fd < 0) {
         meow_log(MEOW_LOG_ERROR, "audio: alsa open /dev/snd/pcmC0D0p failed errno=%d", errno);
@@ -84,7 +84,8 @@ static int alsa_open(int rate, int ch, int bits)
     struct snd_mask *am = &p.masks[SNDRV_PCM_HW_PARAM_ACCESS - SNDRV_PCM_HW_PARAM_FIRST_MASK];
     memset(am, 0, sizeof *am); pmask(am, SNDRV_PCM_ACCESS_RW_INTERLEAVED);
     struct snd_mask *fm = &p.masks[SNDRV_PCM_HW_PARAM_FORMAT - SNDRV_PCM_HW_PARAM_FIRST_MASK];
-    memset(fm, 0, sizeof *fm); pmask(fm, SNDRV_PCM_FORMAT_S16_LE);
+    memset(fm, 0, sizeof *fm);
+    pmask(fm, bits == 32 ? SNDRV_PCM_FORMAT_S32_LE : SNDRV_PCM_FORMAT_S16_LE);
     struct snd_mask *sm = &p.masks[SNDRV_PCM_HW_PARAM_SUBFORMAT - SNDRV_PCM_HW_PARAM_FIRST_MASK];
     memset(sm, 0, sizeof *sm); pmask(sm, SNDRV_PCM_SUBFORMAT_STD);
     pivset(&p.intervals[SNDRV_PCM_HW_PARAM_CHANNELS - SNDRV_PCM_HW_PARAM_FIRST_INTERVAL],
@@ -99,13 +100,14 @@ static int alsa_open(int rate, int ch, int bits)
         return -1;
     }
     ioctl(fd, SNDRV_PCM_IOCTL_PREPARE, 0);
-    meow_log(MEOW_LOG_INFO, "audio: alsa open ok rate=%d ch=%d (direct debug)", rate, ch);
+    meow_log(MEOW_LOG_INFO, "audio: alsa open ok rate=%d ch=%d bits=%d (direct debug)", rate, ch, bits);
     return fd;
 }
 #endif
 
 /* 写 WAV 头（44 字节标准 PCM 布局：RIFF/WAVE/fmt(16)/data）。
- * fmt(16) = format(2) ch(2) sample_rate(4) byte_rate(4) block_align(2) bits(2)。 */
+ * fmt(16) = format(2) ch(2) sample_rate(4) byte_rate(4) block_align(2) bits(2)。
+ * §19：bits 16/32 均合法（32=flac >16bit 的 S32 满幅样本）。 */
 static void file_write_header(int fd, int rate, int ch, int bits, uint32_t data_len)
 {
     unsigned char h[44];
@@ -174,12 +176,16 @@ int audio_out_open(int sample_rate, int channels, int bits)
 #endif
     }
 
-    /* 默认：SINK_AUDIOD（meow_audiod 独占服务）。v1 SDK 声源格式 S16（minimp3 输出即 S16_LE）。 */
-    if (bits != 16) {
-        meow_log(MEOW_LOG_ERROR, "audio: audiod open: bits=%d unsupported (v1 S16 only)", bits);
+    /* 默认：SINK_AUDIOD（meow_audiod 独占服务）。§19：bits 16→S16 / 32→S32
+     * （flac >16bit 由 dr_flac 出 S32 满幅；格式归一/DAC 原生率跟随在 audiod 侧）。 */
+    int fmt;
+    if (bits == 16)      fmt = AUDIO_FMT_S16;
+    else if (bits == 32) fmt = AUDIO_FMT_S32;
+    else {
+        meow_log(MEOW_LOG_ERROR, "audio: audiod open: bits=%d unsupported (16/32)", bits);
         return -1;
     }
-    int sid = meow_audio_open(sample_rate, channels, AUDIO_FMT_S16);
+    int sid = meow_audio_open(sample_rate, channels, fmt);
     if (sid < 0) {
         meow_log(MEOW_LOG_ERROR, "audio: audiod open failed rc=%d rate=%d ch=%d (audiod 不在?)",
                  sid, sample_rate, channels);
@@ -199,7 +205,7 @@ int audio_out_open(int sample_rate, int channels, int bits)
     return 0;
 }
 
-int audio_out_write(const short *samples, int frames)
+int audio_out_write(const void *samples, int frames)
 {
     if (g_app_quit) return -1;
     if (g_sink == SINK_NULL || g_sink < 0) return frames;
@@ -252,11 +258,11 @@ int audio_out_pause(int paused)
         meow_log(MEOW_LOG_WARN, "audio: audiod pause sid=%d rc=%d (stream dead?)", g_sid, rc);
         return 0;
     }
-    /* 恢复失败 = 流已死 → 重开 */
+    /* 恢复失败 = 流已死 → 重开（格式按本次 open 的 bits 还原：16→S16 / 32→S32） */
     meow_log(MEOW_LOG_WARN, "audio: audiod resume sid=%d rc=%d -> reopen", g_sid, rc);
     meow_audio_close(g_sid);
     g_sid = 0;
-    int sid = meow_audio_open(g_rate, g_ch, AUDIO_FMT_S16);
+    int sid = meow_audio_open(g_rate, g_ch, g_bits == 32 ? AUDIO_FMT_S32 : AUDIO_FMT_S16);
     if (sid < 0) {
         meow_log(MEOW_LOG_ERROR, "audio: audiod reopen failed rc=%d rate=%d ch=%d", sid, g_rate, g_ch);
         return -1;