chore(fw): M56 重编 5 件受源码变动影响的产物 + 钉值回写 + 可复现打包器（0.8.51）

- 重编 netmgrd(M54 ACL)/audiod(M55 BT 增益 + M52 bind 失败即退)/launcherd(M52 multi_font 收口)/
  watchdog(M52 资源告警)；meow_audio 源码未变，重编逐字节相同（md5 不变）
- fw_content.conf：5 条 md5 回写 + meow_power desc 去掉「policy 期3桩」（已实装）
- 新增 scripts/build/repack_repro.sh：mksquashfs -repro-time + genisoimage -creation-date
  + mtime 归一化 + 半成品防护（先写暂存再 mv、体积下限自检）
- build_fw_apps.sh：优先走可复现打包器、XIMAGE/TMPDIR 可在干净 checkout/worktree 覆盖
- rebuild_binaries.sh：新增 watchdog 目标（build_watchdog.sh 的 ROOT/.tools 在 worktree 不存在）

scripts/build/rebuild_binaries.sh

@@ -23,9 +23,9 @@
 #   COMPAT_HOME     兼容 HOME 目录（默认 ${TMPDIR:-$HOME/tmp}/meow-build-home）
 #
 # 用法：
-#   bash scripts/build/rebuild_binaries.sh                # 全部 5 组
+#   bash scripts/build/rebuild_binaries.sh                # 全部 6 组
 #   bash scripts/build/rebuild_binaries.sh bootmenu       # 只编指定的（可多个）
-# 组件名：bootmenu netmgrd audiod audio launcherd
+# 组件名：bootmenu netmgrd audiod audio launcherd watchdog
 set -u
 
 ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
@@ -118,8 +118,8 @@ report() {
     printf '   %-44s %8s B  %s\n' "$1" "$(stat -c%s "$f")" "$(md5sum "$f" | cut -d' ' -f1)"
 }
 
-do_bootmenu=0; do_netmgrd=0; do_audiod=0; do_audio=0; do_launcherd=0
-if [ $# -eq 0 ]; then do_bootmenu=1; do_netmgrd=1; do_audiod=1; do_audio=1; do_launcherd=1; fi
+do_bootmenu=0; do_netmgrd=0; do_audiod=0; do_audio=0; do_launcherd=0; do_watchdog=0
+if [ $# -eq 0 ]; then do_bootmenu=1; do_netmgrd=1; do_audiod=1; do_audio=1; do_launcherd=1; do_watchdog=1; fi
 for a in "$@"; do
     case "$a" in
         bootmenu) do_bootmenu=1 ;;
@@ -127,7 +127,8 @@ for a in "$@"; do
         audiod) do_audiod=1 ;;
         audio) do_audio=1 ;;
         launcherd) do_launcherd=1 ;;
-        *) die "未知组件: $a（bootmenu netmgrd audiod audio launcherd）" ;;
+        watchdog) do_watchdog=1 ;;
+        *) die "未知组件: $a（bootmenu netmgrd audiod audio launcherd watchdog）" ;;
     esac
 done
 
@@ -143,5 +144,11 @@ echo "   ZIG=$ZIG ($("$ZIG" version 2>/dev/null || echo '?'))"
 [ "$do_audiod" = 1 ] && { run audiod patch_v2/meow_audiod bash build_audiod.sh; report patch_v2/meow_audiod/meow_audiod; }
 [ "$do_audio" = 1 ] && { run audio patch_v2/meow_audiod bash build_audiod.sh cli; report patch_v2/meow_audiod/meow_audio; }
 [ "$do_launcherd" = 1 ] && { ensure_ui_a; run launcherd patch_v2/meow_launcherd bash build_launcher.sh; report patch_v2/meow_launcherd/meow_launcherd; }
+# watchdog：不走 build_watchdog.sh —— 它按自身位置推 ROOT=../.. 再取 <root>/.tools/zig-mipsel-cc，
+# 该符号链接只在主 checkout 里（worktree 没有），直接跑会「找不到编译器」。这里按它的同一组参数
+# （-Os -Wall -Wextra -static + MEOW_TIME32_LIBC_OVERRIDES + ../sdk/meow_time32.c）显式调用 $ZIGCC。
+[ "$do_watchdog" = 1 ] && { run watchdog patch_v2/meow_watchdog "$ZIGCC" -Os -Wall -Wextra -static \
+    -I../meow_launcherd -DMEOW_TIME32_LIBC_OVERRIDES meow_watchdog.c ../sdk/meow_time32.c -o meow_watchdog
+    report patch_v2/meow_watchdog/meow_watchdog; }
 
 echo "==> 完成。产物自证：bash scripts/build/verify_fingerprints.sh"