Distributed confirmation dialog: all GUIs open on WAIT_USER, server closes all

- Browser: OK button sends Confirm without closing dialog; Escape blocked;
  dialog closes when state leaves WAIT_USER (server-driven).
- PyQt: non-blocking QDialog replaces blocking QMessageBox; OK sends Confirm
  without closing; dialog closed by server state change or on disconnect.
- ws_client.py: remove deprecated loop= params from websockets.connect() and
  asyncio.ensure_future() (same fix already applied to ws_server.py) so the
  PyQt client can actually connect with websockets >= 10.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Tqxrk8uj4M3w3d3eXm3xK8

web/index.html

@@ -100,8 +100,8 @@
 
 <dialog id="sud-message-dialog">
 	<p id="sud-message-text"></p>
-	<form method="dialog">
-		<button value="ok">OK</button>
+	<form>
+		<button id="sud-message-ok" type="button">OK</button>
 	</form>
 </dialog>