fix: don't re-announce boot/shutdown on SIGHUP restart

Setting args.boot = False after sending the boot message was dead code: the
SIGHUP restart re-execs via os.execv(sys.argv[0], sys.argv) with the original
argv, so the re-launched process re-parsed -b and announced a boot again. The
exiting process also sent a spurious shutdown (send_shutdown armed by -b), so
each config reload looked like a host reboot to the server.

Strip -b/--boot from the argv passed to execv, and skip the shutdown message
in cleanup() when dorestart is set. A real SIGTERM/SIGINT shutdown still sends
shutdown as before.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

hbd/client/main.py

@@ -486,7 +486,8 @@ async def cleanup(connections: List[AsyncConnection]):
     logger.info("Cleaning up connections")
     
     target = next((c for c in connections if c.transport), connections[0] if connections else None)
-    if target and send_shutdown:
+    # A SIGHUP restart is not a host shutdown, so don't announce one.
+    if target and send_shutdown and not dorestart:
         try:
             await target.sendto({"shutdown": 1, "acks": target.ackcount})
         except Exception as e:
@@ -564,7 +565,6 @@ async def async_main(args, config):
         boot_msg = {}
         if args.boot:
             boot_msg["boot"] = 1
-            args.boot = False  # Clear boot flag so we don't send it again in main loop
             send_shutdown = True
         if args.message:
             boot_msg["service"] = "service"
@@ -793,7 +793,10 @@ def main(argv=None):
     # Handle restart
     if dorestart:
         logging.info("Restarting...")
-        os.execv(sys.argv[0], sys.argv)
+        # Drop -b/--boot so the re-exec'd process doesn't re-announce a boot;
+        # a SIGHUP restart is not a host reboot.
+        restart_argv = [sys.argv[0]] + [a for a in sys.argv[1:] if a not in ("-b", "--boot")]
+        os.execv(restart_argv[0], restart_argv)
     
     sys.exit(exit_code)