fix(daemon): 串行化 bat-status.json 的读-改-写

watch 循环线程（update_daemon_status/update_daemon_progress）与 RPC 处理线程
（update_daemon_state_only）都会对状态文件做“读→改字段→写回”。单次写虽原子，
但整段读-改-写非原子，无互斥时并发线程会 last-writer-wins 丢失对方的字段更新。

新增进程级 DAEMON_STATUS_FILE_LOCK，三处读-改-写函数入口统一获取该锁串行化
（锁中毒时取 into_inner 继续，不 panic）。

对应 issue #18 维护清单 3-4。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

infrastructure/src/bin/bat_official_sync.rs

@@ -3042,6 +3042,19 @@ fn read_daemon_status_file(path: &Path) -> anyhow::Result<Option<DaemonStatusFil
     Ok(Some(serde_json::from_slice(&bytes)?))
 }
 
+/// 串行化 `bat-status.json` 的读-改-写。
+///
+/// watch 循环线程（`update_daemon_status`/`update_daemon_progress`）与 RPC 处理线程
+/// （`update_daemon_state_only`）都会更新状态文件；单次写虽原子，但“读→改字段→写回”
+/// 整体非原子，无此锁会因 last-writer-wins 丢失并发线程的字段更新。
+static DAEMON_STATUS_FILE_LOCK: Mutex<()> = Mutex::new(());
+
+fn lock_daemon_status_file() -> std::sync::MutexGuard<'static, ()> {
+    DAEMON_STATUS_FILE_LOCK
+        .lock()
+        .unwrap_or_else(|poison| poison.into_inner())
+}
+
 fn write_daemon_status_file(path: &Path, status: &DaemonStatusFile) -> anyhow::Result<()> {
     write_file_atomic(
         path,
@@ -3054,6 +3067,7 @@ fn write_daemon_status_file(path: &Path, status: &DaemonStatusFile) -> anyhow::R
 }
 
 fn update_daemon_status(state_dir: &Path, update: DaemonStatusUpdate<'_>) -> anyhow::Result<()> {
+    let _guard = lock_daemon_status_file();
     let status_path = daemon_status_path(state_dir);
     let mut status = read_daemon_status_file(&status_path)?.unwrap_or_else(|| DaemonStatusFile {
         version: DAEMON_STATUS_VERSION,
@@ -3099,6 +3113,7 @@ fn update_daemon_status(state_dir: &Path, update: DaemonStatusUpdate<'_>) -> any
 }
 
 fn update_daemon_progress(state_dir: &Path, event: &OfficialUpdateProgress) -> anyhow::Result<()> {
+    let _guard = lock_daemon_status_file();
     let status_path = daemon_status_path(state_dir);
     let Some(mut status) = read_daemon_status_file(&status_path)? else {
         return Ok(());
@@ -3128,6 +3143,7 @@ fn update_daemon_progress(state_dir: &Path, event: &OfficialUpdateProgress) -> a
 }
 
 fn update_daemon_state_only(state_dir: &Path, state: &str) -> anyhow::Result<()> {
+    let _guard = lock_daemon_status_file();
     let status_path = daemon_status_path(state_dir);
     let Some(mut status) = read_daemon_status_file(&status_path)? else {
         return Ok(());