Filter DA1 responses from replay buffer on WebSocket connect

The replay buffer can contain DA1/DA2 terminal attribute responses
(e.g., \x1b[?1;10;0c) that were captured before filtering was added
to the session classes. These responses appear as visible text like
'1;10;0c' when sent to the client on reconnect.

This adds an additional filter pass when sending the replay buffer,
ensuring no DA1 responses reach the client regardless of when they
were captured.

tests/test_cli.py

@@ -40,6 +40,7 @@ class TestCLI:
 
     def test_cli_runs_default_shell(self, monkeypatch):
         import os
+
         calls: dict[str, object] = {}
 
         class FakeServer: