fix: market_watch/mr_scanner/s2_scanner 统一加装自愈式单例守卫

- 与price_monitor同模式: 新鲜实例在跑则退出, 卡死超时则SIGKILL接管
- market_watch 600s / 扫描器 1500s 阈值
- 落实2026-08-05重型任务资源约束铁律第4条

deploy/profile-scripts/mr_scanner.py

@@ -284,8 +284,41 @@ def check_vmr(klines, mkt_adx=None):
     }
 
 
+def _singleton_guard(max_age_sec, script_tag):
+    """自愈式单例守卫（2026-08-05 进程堆积事故后统一加装）"""
+    import subprocess as _sp, os as _os, sys as _sys
+    my_pid = _os.getpid()
+    try:
+        out = _sp.run(["ps", "-C", "python3", "-o", "pid,etimes,cmd"],
+                      capture_output=True, text=True, timeout=10).stdout
+        for line in out.splitlines():
+            if script_tag not in line:
+                continue
+            parts = line.split(None, 2)
+            if len(parts) < 3:
+                continue
+            try:
+                pid = int(parts[0]); age = int(parts[1])
+            except ValueError:
+                continue
+            if pid == my_pid:
+                continue
+            if age > max_age_sec:
+                try:
+                    _os.kill(pid, 9)
+                    print(f"[guard] SIGKILL卡死实例 pid={pid} age={age}s", flush=True)
+                except ProcessLookupError:
+                    pass
+            else:
+                print(f"[guard] 已有新鲜实例 pid={pid} age={age}s 在跑, 本实例退出", flush=True)
+                _sys.exit(0)
+    except Exception as _e:
+        print(f"[guard] 守卫异常(放行): {_e}", flush=True)
+
+
 def main():
     force = "--force" in sys.argv
+    _singleton_guard(1500, "mr_scanner.py")
     top_n = TOP_N
     if "--top" in sys.argv:
         try: