test(ncm): M9 分类/登录门宿主单测（83 断言）+ 传输层归一 4 例 + REPORT §41

- bench/session_gate_sim.c（新）：真实 core + ncm_http_request 桩，覆盖
  A 错误分类矩阵（-4/-5/-6/-17/裸 mbedtls vs -13/其它）、B HTTP 状态矩阵
  （401/403 vs 5xx/429 vs 3xx/4xx）、C 登录门 + 启动决策（无网→离线、无会话→扫码）、
  D 真实 ncm_api 状态/业务码映射（含 -460→SVC、301/302→AUTH）、
  E 真实 ncm_login_status_check/refresh 映射、F 会话密钥稳定性（换 MAC 仍可解、
  旧 MAC 密文可解且自动迁移）。83 PASS / 0 FAIL，0 真实请求。
- bench/http_truncate_sim.c：追加 4 例传输层归一（握手 fatal alert→NET、握手超时→TIMEOUT、
  读 fatal alert→NET、CA 失败→TLS），原 8 例截断守卫零回归（12 PASS）。
- build_ncm_sims.sh：window/search/plpage/apicache/cookie_refresh 链入 ncm_session.o
  （appstate/api/login 新依赖），新增 session_gate_sim 构建与运行。
- test_ncm_core.c：采用 M8 分支的 $TMPDIR 适配（Termux /tmp 不可写；合并时以 M8 为准）。
- 相关 sim 头注释同步链接命令（ncm_apicache.o/ncm_session.o）。
- REPORT §41：判定点调用链与行号、根因证据、实现、验证矩阵与诚实出入
  （mipsel/真机未跑；app.c 宿主不可编译的既有原因；403/-460 取舍）。

验证：test_ncm_core_host 139 PASS/0 FAIL；session_gate_sim 83 PASS；
http_truncate_sim 12 PASS；window/search/apicache/cookie_refresh sim 通过；
核心 12 TU + 应用 13 TU（-Wall -Wextra）0 warning。

patch_v2/ncm_app/build_ncm_sims.sh

@@ -72,7 +72,7 @@ gcc -O2 -ffunction-sections -DJSMN_HEADER -I. -I../sdk -I../meow_launcherd \
 gcc -O2 -ffunction-sections -DJSMN_HEADER -I. -I../sdk -I../meow_launcherd \
     -Icore -Ivendor/jsmn -Ivendor/mbedtls/include -c app/logic/songmeta.c -o /tmp/ws_meta.o
 gcc -O2 -Wl,--gc-sections -o window_sim /tmp/ws.o /tmp/ws_app.o /tmp/ws_meta.o \
-    out/core-host/ncm_apicache.o -lpthread   # appstate.c 调 ncm_apicache_init/clear（自包含模块）
+    out/core-host/ncm_apicache.o out/core-host/ncm_session.o -lpthread   # appstate.c 调 ncm_apicache_*/ncm_gate_decide
 run_sim window_sim
 
 echo "==> build plpage_sim（歌单页懒加载分页 + 加载后列表刷新；真实 playlist.c 全链路 + 宿主 SDK，0 网络。"
@@ -84,6 +84,7 @@ for f in bench/plpage_sim.c app/ui/playlist.c app/logic/appstate.c app/logic/son
 done
 gcc -O2 -Wl,--gc-sections -Wl,--wrap=meow_ui_paint_full -o plpage_sim \
     /tmp/pp_plpage_sim.o /tmp/pp_playlist.o /tmp/pp_appstate.o /tmp/pp_songmeta.o /tmp/pp_chrome.o /tmp/pp_ncm_colors.o \
+    out/core-host/ncm_session.o \
     out/host/sdk_*.o -lz -lpthread -lm
 run_sim plpage_sim
 
@@ -93,7 +94,7 @@ gcc -O2 -ffunction-sections -DJSMN_HEADER -I. -I../sdk -I../meow_launcherd -Icor
 gcc -O2 -ffunction-sections -DJSMN_HEADER -I. -I../sdk -I../meow_launcherd \
     -Icore -Ivendor/jsmn -c app/logic/appstate.c -o /tmp/sh_app.o
 gcc -O2 -Wl,--gc-sections -o search_sim /tmp/sh.o /tmp/sh_app.o \
-    out/core-host/ncm_apicache.o -lpthread   # appstate.c 调 ncm_apicache_init/clear
+    out/core-host/ncm_apicache.o out/core-host/ncm_session.o -lpthread   # appstate.c 调 ncm_apicache_*/ncm_gate_decide
 run_sim search_sim
 
 echo "==> build cache_evict_sim"
@@ -110,7 +111,8 @@ gcc -O2 -Wall -Wextra -DJSMN_HEADER -I. -Icore -I../sdk -I../meow_launcherd \
 # 故不链 ncm_http.o）+ jsmn + 宿主 mbedtls；核心对象从 out/core-host/*.o 取（含 ncm_apicache.o）。
 gcc -O2 -o apicache_sim /tmp/ac.o \
     $(ls out/core-host/ncm_api.o out/core-host/ncm_req.o out/core-host/ncm_crypto.o \
-          out/core-host/ncm_json.o out/core-host/ncm_common.o out/core-host/ncm_apicache.o) \
+          out/core-host/ncm_json.o out/core-host/ncm_common.o out/core-host/ncm_apicache.o \
+          out/core-host/ncm_session.o) \
     out/core-host/jsmn_impl.o \
     -Lout/mbedtls/host -lmbedtls -lmbedx509 -lmbedcrypto -lpthread -lm
 run_sim apicache_sim
@@ -122,11 +124,23 @@ gcc -O2 -Wall -Wextra -DJSMN_HEADER -I. -Icore -I../sdk -I../meow_launcherd \
 gcc -O2 -o cookie_refresh_sim /tmp/crs.o \
     $(ls out/core-host/ncm_login.o out/core-host/ncm_req.o out/core-host/ncm_crypto.o \
           out/core-host/ncm_json.o out/core-host/ncm_common.o out/core-host/ncm_store.o \
-          out/core-host/v_qrcodegen.o) \
+          out/core-host/ncm_session.o out/core-host/v_qrcodegen.o) \
     out/core-host/jsmn_impl.o \
     -Lout/mbedtls/host -lmbedtls -lmbedx509 -lmbedcrypto -lpthread -lm
 run_sim cookie_refresh_sim
 
+echo "==> build session_gate_sim（M9 离线会话保持/登录门：分类矩阵 + HTTP 状态/业务码映射 + 会话密钥稳定性；0 真实网络）"
+mkdir -p out/chk
+gcc -O2 -Wall -Wextra -DJSMN_HEADER -I. -Icore -Ivendor/jsmn -Ivendor/mbedtls/include \
+    -c bench/session_gate_sim.c -o out/chk/sg.o
+gcc -O2 -o session_gate_sim out/chk/sg.o \
+    $(ls out/core-host/ncm_api.o out/core-host/ncm_login.o out/core-host/ncm_req.o \
+          out/core-host/ncm_crypto.o out/core-host/ncm_json.o out/core-host/ncm_common.o \
+          out/core-host/ncm_store.o out/core-host/ncm_apicache.o out/core-host/ncm_session.o) \
+    out/core-host/jsmn_impl.o out/core-host/v_qrcodegen.o \
+    -Lout/mbedtls/host -lmbedtls -lmbedx509 -lmbedcrypto -lpthread -lm
+run_sim session_gate_sim
+
 echo "==> build account_cookie_sim (§NEW 临期续期决策；真实 account.c + 外围桩，0 真实网络)"
 gcc -O2 -Wall -Wextra -DJSMN_HEADER -I. -Iapp -Icore -I../sdk -I../meow_launcherd \
     -Ivendor/jsmn -Ivendor/qrcodegen/c -Ivendor/mbedtls/include \