feat(ncm §24): 流媒体客户端边下边播阶段3——.part断点续传(Range/206/200/416)+LRU防淘汰(.tmp/.part跳过)+失败重试1次退避

按 devdocs/plan/NCM_STREAM_PLAY.md §8 阶段3：
- .part 断续传：中断留 .part，续传带 Range，206 追加 / 200 丢头段 / 416 删残留整首重下；URL 每次新拉
- LRU 防淘汰：evict/total_bytes 跳过 .tmp/.part（在播文件不被动过）
- 失败重试：预缓冲前网络失败重试 1 次，退避 800ms，重试拿新签名 URL（风控：0 真实请求，未部署）
- 顺手修：gb_to_bytes 返回 int 溢出致默认 10GB 上限失效 -> uint64_t
- 验证：stream_sim(续传 PCM 金标准+全矩阵)/player_flow_sim(P9/P10/P11)/cache_evict_sim(case7/8)/test_ncm_core 宿主+qemu-mipsel 全 PASS；build_ncm.sh 0 warning；ncm_host 离屏正常

md5 ncm f8f316a1e6f3bdd8f6b5921fdbb3f3a2

patch_v2/ncm_app/bench/cache_evict_sim.c

@@ -195,6 +195,96 @@ int main(void)
     CHECK(ncm_cache_total_bytes(&g_c) == 0, "total=%llu after clear (expect 0)",
           (unsigned long long)ncm_cache_total_bytes(&g_c));
 
+    /* ⑦ 阶段3：播放中的 .tmp / 中断残体 .part 不被 LRU 淘汰，且不计入池占用。
+     *   「正在下载播放的文件」= .tmp（写穿缓存态）；「上次中断的可续传残体」= .part。
+     *   二者在 evict/total_bytes 中被跳过——防正在听的歌被缓存上限挤掉（§5.1）。 */
+    printf("== case 7: evict skips .tmp/.part (playing file not evicted; stage3 §5.1) ==\n");
+    cleanup();
+    ncm_cache_set_limit_gb(&g_c, 1);   /* 1GB（int 内，避免既有 gb_to_bytes int 溢出 bug 干扰本用例） */
+    make_cached("a", ".mp3", mb(600), 1000);   /* 600MB 最旧 */
+    make_cached("b", ".mp3", mb(600), 1100);   /* 600MB */
+    /* 在途 .tmp（边下边播写穿缓存态）：song_b.mp3.tmp */
+    {
+        char p[600];
+        ncm_cache_path(&g_c, "b", ".mp3", p, sizeof p);
+        strncat(p, ".tmp", sizeof p - strlen(p) - 1);
+        int fd = open(p, O_WRONLY | O_CREAT, 0644);
+        if (ftruncate(fd, (off_t)mb(300)) != 0) printf("  truncate tmp err\n");
+        close(fd);
+    }
+    /* 中断残体 .part（可续传）：song_d.mp3.part */
+    {
+        char p[600];
+        ncm_cache_path(&g_c, "d", ".mp3", p, sizeof p);
+        strncat(p, ".part", sizeof p - strlen(p) - 1);
+        int fd = open(p, O_WRONLY | O_CREAT, 0644);
+        if (ftruncate(fd, (off_t)mb(300)) != 0) printf("  truncate part err\n");
+        close(fd);
+    }
+    CHECK(ncm_cache_total_bytes(&g_c) == mb(1200),
+          "total excludes .tmp/.part (=%lluMB, expect 1200MB)",
+          (unsigned long long)(ncm_cache_total_bytes(&g_c) / (1024*1024)));
+    ncm_cache_evict(&g_c);
+    CHECK(!cached_exists("a", ".mp3"), "oldest committed a evicted");
+    CHECK(cached_exists("b", ".mp3"), "b kept (<=limit)");
+    /* .tmp/.part 文件仍在（未被打包进 LRU 淘汰） */
+    {
+        char tp[600], pp[600];
+        ncm_cache_path(&g_c, "b", ".mp3", tp, sizeof tp); strncat(tp, ".tmp", sizeof tp-strlen(tp)-1);
+        ncm_cache_path(&g_c, "d", ".mp3", pp, sizeof pp); strncat(pp, ".part", sizeof pp-strlen(pp)-1);
+        struct stat st;
+        CHECK(stat(tp, &st) == 0, "playing .tmp survives evict");
+        CHECK(stat(pp, &st) == 0, "resume .part survives evict");
+    }
+    CHECK(ncm_cache_total_bytes(&g_c) == mb(600),
+          "total after evict excludes partials (=%lluMB, expect 600MB)",
+          (unsigned long long)(ncm_cache_total_bytes(&g_c) / (1024*1024)));
+
+    /* ⑧ 阶段3：部分文件 API 快检——part_size 检测 / open_resume 追加 / abort_part 保留 /
+     *   abort 删除 的命名契约（供 player_manager 续传链路）。 */
+    printf("== case 8: .part resume API contract (stage3 §5.2) ==\n");
+    cleanup();
+    {
+        /* 用 ncm_cache_open_resume 打开上一步遗留 .part 无（已 cleanup）——先造一个真 .part */
+        char p[600];
+        ncm_cache_path(&g_c, "r", ".mp3", p, sizeof p);
+        snprintf(p + strlen(p), sizeof p - strlen(p), ".part");
+        int fd = open(p, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+        if (fd >= 0) { (void)!write(fd, "ABCDEF", 6); close(fd); }
+        uint64_t sz = 0;
+        CHECK(ncm_cache_part_size(&g_c, "r", ".mp3", &sz) == NCM_OK && sz == 6,
+              "part_size reports 6 (got %llu)", (unsigned long long)sz);
+        ncm_cache_writer_t *w = NULL;
+        CHECK(ncm_cache_open_resume(&g_c, "r", ".mp3", &w) == NCM_OK, "open_resume ok");
+        CHECK(ncm_cache_write(w, (const unsigned char *)"GH", 2) == NCM_OK, "resume append write");
+        CHECK(ncm_cache_commit(w) == NCM_OK, "resume commit (rename .part->final)");
+        /* commit 后 .part 转正：lookup 命中且内容=ABCDEFGH，.part 消失 */
+        char path[600];
+        CHECK(ncm_cache_lookup(&g_c, "r", ".mp3", path, sizeof path) == NCM_OK, "resume commit lookup hit");
+        FILE *f = fopen(path, "rb");
+        char buf[16] = {0}; int n = 0;
+        if (f) { n = (int)fread(buf, 1, sizeof buf - 1, f); fclose(f); }
+        CHECK(n == 8 && memcmp(buf, "ABCDEFGH", 8) == 0, "committed bytes=%.8s (expect ABCDEFGH)", buf);
+        CHECK(ncm_cache_part_size(&g_c, "r", ".mp3", &sz) == NCM_ERR_NOENT, ".part gone after commit");
+        /* abort_part 保留残体 / abort 删除：造两个 .part 分别走两路 */
+        ncm_cache_path(&g_c, "s", ".mp3", p, sizeof p);
+        snprintf(p + strlen(p), sizeof p - strlen(p), ".part");
+        fd = open(p, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+        if (fd >= 0) { (void)!write(fd, "1234", 4); close(fd); }
+        CHECK(ncm_cache_open_resume(&g_c, "s", ".mp3", &w) == NCM_OK, "s open_resume");
+        CHECK(ncm_cache_abort_part(w) == NCM_OK, "s abort_part");
+        struct stat st2;
+        CHECK(stat(p, &st2) == 0, "abort_part keeps .part (resumable)");
+        CHECK(ncm_cache_open_resume(&g_c, "s", ".mp3", &w) == NCM_OK, "s reopen_resume");
+        CHECK(ncm_cache_abort(w) == NCM_OK, "s abort (delete)");
+        CHECK(stat(p, &st2) != 0, "abort deletes .part");
+        /* part_remove 显式删除 */
+        fd = open(p, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+        if (fd >= 0) { (void)!write(fd, "x", 1); close(fd); }
+        CHECK(ncm_cache_part_remove(&g_c, "s", ".mp3") == NCM_OK, "part_remove ok");
+        CHECK(stat(p, &st2) != 0, "part_remove deleted .part");
+    }
+
     cleanup();
     printf("%s\n", g_fail ? "RESULT: FAIL" : "RESULT: PASS");
     return g_fail ? 1 : 0;