fix(reliability): clear boot marker on graceful shutdown (I1)

payload/user/remote_access/pager-webui/server.py

@@ -5106,6 +5106,17 @@ def check_boot_marker():
         return False
 
 
+def _clear_boot_marker():
+    """Best-effort: a clean shutdown must not read as an unexpected reboot."""
+    marker = globals().get('BOOT_MARKER')
+    if not marker:
+        return
+    try:
+        os.unlink(marker)
+    except Exception:
+        pass
+
+
 def startup_env_check(attempts=STARTUP_CHECK_ATTEMPTS,
                       delay=STARTUP_CHECK_DELAY):
     """Run and print the startup contract, allowing boot dependencies time.
@@ -7143,6 +7154,10 @@ def _request_shutdown(signum=None, frame=None):
     LIVE_STOP.set()
     HEALTH_STOP.set()
     _recon_hopper_stop.set()
+    try:
+        _clear_boot_marker()
+    except Exception:
+        pass
 
 
 def _uci_iface_present(name):